Video display system

ABSTRACT

A video display system includes a plurality of primary color light sources; and a spatial light modulator (SLM) for modulating an illumination light emitted from at least one of the plurality of primary light sources. The video display system further includes a display controller for controlling a process to display a sequence of video images within a period of one frame comprising each of a plurality of primary colors and each of a plurality of complementary colors to minimize a number of emissions of each of the plurality of primary color light sources and also displaying the video images of the colors of the plurality of primary colors and the plurality of complementary colors in sequence.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Non-provisional Application of a ProvisionalApplication 61/069,420 filed on Mar. 15, 2008 and a Continuation in PartApplication of another Non-provisional patent application Ser. No.11/827,455 filed on Jul. 11, 2007 and Ser. No. 11/121,543 filed on May4, 2005 issued into U.S. Pat. No. 7,268,932 and another Non-provisionalapplication Ser. No. 10/698,620 filed on Nov. 1, 2003 now abandoned. Theapplication Ser. No. 11/121,543 is a Continuation In Part (CIP)Application of three previously filed Applications. These threeapplications are Ser. No. 10/698,620 filed on Nov. 1, 2003, Ser. No.10/699,140 filed on Nov. 1, 2003 now issued into U.S. Pat. No.6,862,127, and Ser. No. 10/699,143 filed on Nov. 1, 2003 now issued intoU.S. Pat. No. 6,903,860 by the Applicant of this patent applications.The disclosures made in these patent applications are herebyincorporated by reference in this patent application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a video display system which generatesand displays the frame signal of an output video signal at a higherframe rate than that of an input video signal from the frame signal of acontinuously inputted video signal.

2. Description of the Related Art

After the dominance of CRT technology in the display industry for over100 years, Flat Panel Display (FPD) and Projection Display have gainedpopularity because of their space efficiency and larger screen size.Projection displays using micro-display technology are gainingpopularity among consumers because of their high picture quality andlower cost. There are two types of micro-displays used for projectiondisplays in the market. One is micro-LCD (Liquid Crystal Display) andthe other is micro-mirror technology. Because a micro-mirror device usesun-polarized light, it produces better brightness than micro-LCD, whichuses polarized light.

Although significant advances have been made in technologies ofimplementing electromechanical micro-mirror devices as spatial lightmodulators, there are still limitations in their high quality imagesdisplay. Specifically, when display images are digitally controlled,image quality is adversely due to an insufficient number of gray scales.

Electromechanical micro-mirror devices have drawn considerable interestbecause of their application as spatial light modulators (SLMs). Aspatial light modulator requires an array of a relatively large numberof micro-mirror devices. In general, the number of required devicesranges from 60,000 to several million for each SLM. Referring to FIG.1A, an image display system 1 including a screen 2 is disclosed in arelevant U.S. Pat. No. 5,214,420. A light source 10 is used to generatelight beams to project illumination for the display images on thedisplay screen 2. The light 9 projected from the light source is furtherconcentrated and directed toward lens 12 by way of mirror 11. Lenses 12,13 and 14 form a beam collimator operative to columnate the light 9 intoa column of light 8. A spatial light modulator 15 is controlled by acomputer through data transmitted over data cable 18 to selectivelyredirect a portion of the light from path 7 toward lens 5 to display onscreen 2. FIG. 1B shows a SLM 15 that has a surface 16 that includes anarray of switchable reflective elements 17, 27, 37, and 47, each ofthese reflective elements is attached to a hinge 30. When the element 17is in an ON position, a portion of the light from path 7 is reflectedand redirected along path 6 to lens 5 where it is enlarged or spreadalong path 4 to impinge on the display screen 2 to form an illuminatedpixel 3. When the element 17 is in an OFF position, the light isreflected away from the display screen 2 and, hence, pixel 3 is dark.

The on-and-off states of the micromirror control scheme, as thatimplemented in the U.S. Pat. No. 5,214,420 and in most conventionaldisplay systems, impose a limitation on the quality of the display.Specifically, applying the conventional configuration of a controlcircuit limits the gray scale gradations produced in a conventionalsystem (PWM between ON and OFF states), limited by the LSB (leastsignificant bit, or the least pulse width). Due to the ON-OFF statesimplemented in the conventional systems, there is no way of providing ashorter pulse width than the duration represented by the LSB. The leastquantity of light, which determines the gray scale, is the lightreflected during the least pulse width. The limited levels of the grayscale lead to a degradation of the display image

Specifically, FIG. 1C exemplifies, as related disclosures, a circuitdiagram for controlling a micromirror according to U.S. Pat. No.5,285,407. The control circuit includes memory cell 32. Varioustransistors are referred to as “M*” where “*” designates a transistornumber and each transistor is an insulated gate field effect transistor.Transistors M5, and M7 are p-channel transistors; transistors, M6, M8,and M9 are n-channel transistors. The capacitances, C1 and C2, representthe capacitive loads in the memory cell 32. The memory cell 32 includesan access switch transistor M9 and a latch 32 a based on a Static RandomAccess switch Memory (SRAM) design. All access transistors M9 on a Rowline receive a DATA signal from a different Bit-line 31 a. Theparticular memory cell 32 is accessed for writing a bit to the cell byturning on the appropriate row select transistor M9, using the ROWsignal functioning as a Word-line. Latch 32 a consists of twocross-coupled inverters, M5/M6 and M7/M8, which permit two stable statesthat include a state 1 when is Node A high and Node B low, and a state 2when Node A is low and Node B is high.

The control circuit positions the micro-mirrors to be at either an ON oran OFF angular orientation, as that shown in FIG. 1A. The brightness,i.e., the number of gray scales of display for a digitally control imagesystem, is determined by the length of time the micro-mirror stays at anON position. The length of time a micromirror is in an ON position iscontrolled by a multiple bit word.

FIG. 1D shows the “binary time intervals” when controlling micromirrorswith a four-bit word. As shown in FIG. 1D, the time durations haverelative values of 1, 2, 4, 8, which in turn define the relativebrightness for each of the four bits where “1” is the least significantbit and “8” is the most significant bit. According to the controlmechanism as shown, the minimum controllable differences between grayscales for showing different levels of brightness is a represented bythe “least significant bit” that maintains the micromirror at an ONposition.

For example, assuming n bits of gray scales, one time frame is dividedinto 2^(n)−1 equal time periods. For a 16.7-millisecond frame period andn-bit intensity values, the time period is 16.7/(2^(n)−1) milliseconds.

Having established these times for each pixel of each frame, pixelintensities are quantified such that black is a 0 time period, theintensity level represented by the LSB is 1 time period, and the maximumbrightness is 2^(n)−1 time periods. Each pixel's quantified intensitydetermines its ON-time during a time frame. Thus, during a time frame,each pixel with a quantified value of more than 0 is ON for the numberof time periods that correspond to its intensity. The viewer's eyeintegrates the pixel brightness so that the image appears the same as ifit were generated with analog levels of light.

For controlling deflectable mirror devices, the PWM applies data to beformatted into “bit-planes”, with each bit-plane corresponding to a bitweight of the intensity of light. Thus, if the brightness of each pixelis represented by an n-bit value, each frame of data has then-bit-planes. Then, each bit-plane has a 0 or 1 value for each mirrorelement. According to the PWM control scheme described in the precedingparagraphs, each bit-plane is independently loaded and the mirrorelements are controlled according to bit-plane values corresponding tothe value of each bit during one frame. Specifically, the bit-planeaccording to the LSB of each pixel is displayed for 1 time period.

Among conventional display systems, there is a system which generatesand displays the frame signal of an output video signal at a higherframe rate than that of an input video signal from the frame signal of acontinuously inputted video signal.

A system which displays a video image using a display device, such as aliquid crystal display (LCD) panel, retains one frame of video imageinformation of each pixel for a single frame period and is enabled todisplay a smooth video image with little shaking of a dynamic image bygenerating and displaying an output video signal with a 120 Hz framerate from an input video signal with a 60 Hz frame rate.

FIG. 2 is a diagram showing an example of generating a 120 Hz high framerate output video signal from a 60 Hz frame-rate input video signal.This example is configured to generate anew the video signal of oneframe on the basis of information from two adjacent frames of an inputvideo signal, insert the generated video signal in between theaforementioned two input video signals, and generate anew a continuousvideo signal, and thereby a higher frame rate output video signal thanthe input video signal is generated. Incidentally, in the example shownin FIG. 2, the video image of the input video signal is the image of aball moving from the bottom left to the top right. Further, the inputtedvideo signal of each frame has 10-bit gray scale data for each pixel,and the video signal of a frame generated from the video signal of thetwo adjacent frames of the input video signal also has 10-bit gray scaledata for each pixel. Therefore, the gray scale level of intensity (i.e.,brightness) perceived by the human eye, in this example, is the samebetween the input video signal and the output video signal.

In order to more smoothly display the motion of a video image, it isdesirable to use a video signal with a higher frame rate to display theimage.

More specifically, the conventional method for generating a continuousvideo signal having a higher frame rate from a video signal continuouslyinputted at a specific frame rate, described above, includes a method ofdetecting the moving portion of the video image from the continuouslyinputted video signal and generating a new video signal of a frame so asto interpolate the motion. The conventional method also includes amethod of generating a video signal of an interpolation frame bydetermining the intensity of each pixel constituting the video image ofa frame to be interpolated on the basis of the change in the intensityinformation of each pixel constituting the aforementioned continuouslyinputted video signal.

Such techniques for generating and displaying the output video signalfrom an input video signal at a higher frame rate than that of the inputvideo signal are disclosed in, among others, U.S. Pat. No. 4,771,331,JP2007-166050A, and WO/1997/046022. In recent years, such techniquesenable the generating and displaying of video signals of a high framerate in excess of 240 Hz without degrading the image quality of a videosignal which is inputted at a 60 Hz frame rate.

Furthermore, in a display system employing a color sequential displaymethod, it is also possible to prevent the color breakup phenomena bycarrying out a display using a high frame rate video signal. In adisplay system such as an LCD display system, however, if a high framerate video signal is generated by a video image processing apparatus,such as a video processor, and if the generated video signal isdisplayed, problems occur such as an increased load taken up by thedisplay processing and lower response speed, thus limiting the simpleimprovement of a frame rate of the video signal to be displayed.

FIG. 3 is a diagram showing an example of generating a 360 Hz high-framerate output video signal from a 60 Hz frame rate input video signal in adisplay system employing a color sequential display method. Morespecifically, the video image of the input video signal is the image inwhich a ball is moving from the bottom left to the top right, also shownin FIG. 3.

Referring to FIG. 3, if the input video signal is a color video signalconstituted by an RGB (red, green and blue) signal and if the videosignal of the frame has 10-bit gray scale data for each of therespective colors R, G and B for each pixel, a high frame rate outputvideo signal is preferably generated so that the video signal of theframe has 10-bit gray scale data for each of the respective colors R, Gand B for each pixel. In order to accomplish this, however, it isnecessary to drastically improve the processing speed of the video imageprocessing apparatus used for generating the new video signal of theframe by processing the input video signal, and to increase the memoryspace used for temporarily storing the video signals of a plurality offrames of the input video signal or the generated video signals of theframes.

Specifically, if an output video signal with a 360 Hz frame rate is tobe generated, and if the video signal of the frame is to have 10-bitgray scale data for each of the respective colors R, G and B, it isnecessary to use a video image processing apparatus having at leastthree times the processing speed and three times the memory space thanwhen generating a 120 Hz frame rate output video signal from a 60 Hzframe rate input video signal, as shown in FIG. 3. This introduces theproblems of an enlarged system size and a substantial cost increase.

Moreover, while it is necessary to provide a display system enabled todisplay a video image at three times the speed of the current rate, ifsuch a system cannot be employed due to the problems described above,the information volume of each frame signal of a video signal to bedisplayed needs to be decreased to a third.

SUMMARY OF THE INVENTION

In consideration of the above-described limitations and difficulties,one aspect of the present invention is to provide a video display systemto increase the gray scale levels of a video image perceived by thehuman eye while decreasing the amount of data in a frame signal requiredto process at a high frame rate for reducing the load of video imageprocessing and display processing of an image display system.

In order to accomplish the aim described above, a video display systemaccording to a first exemplary embodiment of the present inventionincludes a video display system includes a plurality of primary colorlight sources; and a spatial light modulator (SLM) for modulating anillumination light emitted from at least one of the plurality of primarylight sources. The video display system further includes a displaycontroller for controlling a process to display a sequence of videoimages within a period of one frame comprising each of a plurality ofprimary colors and each of a plurality of complementary colors tominimize a number of emissions of each of the plurality of primary colorlight sources and also displaying the video images of the colors of theplurality of primary colors and the plurality of complementary colors insequence.

A video display system according to a second exemplary embodiment of thepresent invention includes a plurality of primary color light sources;and a spatial light modulator (SLM) for modulating an illumination lightemitted from at least one of the plurality of primary light sources,wherein a display controller for controlling a process to display asequence of video images within a period of one frame comprising of eachof a plurality of primary colors and each of a plurality ofcomplementary colors to maximize a number of emissions of each of theplurality of primary color light sources and also displaying the videoimages of the colors of the plurality of primary colors and theplurality of complementary colors in sequence.

A video display system according to a third exemplary embodiment of thepresent invention includes an image processing unit receivescontinuously an input video signal including input frame signals forgenerating an output video signal having a higher frame rate than theinput video signal; and a spatial light modulator (SLM) applies theoutput video signal for modulating an illumination light, wherein theimage processing unit further receives an individual frame signal of theinput video signal into a frame for sequentially displaying a pluralityof sub-frame video images in different colors within a display frame,and the image processing unit further generates the output video signalincludes a frame signal for sequentially displaying the sub-frame videoimages of different colors, wherein a number of gray scale levels of asub-frame video image of each color of the output video signal issmaller, or smaller in a part of sub-frame images, than a number of grayscale levels of a sub-frame video image of each color of the input videosignal.

A video display system according to a fourth exemplary embodiment of thepresent invention includes an image processing unit receivescontinuously an input video signal including input frame signals forgenerating an output video signal including output frame signals havinga higher frame rate than the input frame signals; and a spatial lightmodulator (SLM) applies the output frame signals for modulating anillumination light, wherein the input frame signal comprises signals tosequentially display sub-frame video images of a plurality of colors,and the image processing units generates the output video signalincludes sub-frame signals of the plurality of colors applied to the SLMto carry out a modulation process to sequentially display the sub-framevideo images of the plurality of colors.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described in detail below with reference to thefollowing Figures.

FIG. 1A illustrates the basic principle of a projection display using amicromirror device, as disclosed in a prior art patent;

FIG. 1B is a top view diagram showing the configuration of mirrorelements of a portion of a micromirror array of a projection apparatusdisclosed in a prior art patent.

FIG. 1C is a circuit diagram showing the configuration of a drivecircuit of mirror elements of a projection apparatus disclosed in aprior art patent.

FIG. 1D shows the scheme of Binary Pulse Width Modulation (Binary PWM)of conventional digital micromirrors for generating a grayscale;

FIG. 2 is a diagram showing an example of generating the frame signal ofa 120 Hz high-frame rate output video signal from a 60 Hz frame rateinput video signal;

FIG. 3 is a diagram showing an example of generating a 360 Hz high-framerate output video signal, as a video signal to be displayed, from a 60Hz frame rate input video signal in a display system employing a colorsequential display method;

FIG. 4 is a functional block diagram showing an exemplary configurationof a video display system according to a preferred embodiment of thepresent invention;

FIG. 5 is a functional block diagram showing an exemplary circuitconfiguration of a video display system according to a preferredembodiment of the present invention;

FIG. 6 is a diagram showing the layout of the internal configuration ofan SLM in further detail;

FIG. 7 is a cross-sectional diagram showing an exemplary configurationof an individual pixel element;

FIG. 8 is a diagram showing an exemplary configuration of the circuitfor an individual pixel element;

FIG. 9 is a diagram showing an exemplary operation of an imageprocessing unit according to a first preferred embodiment;

FIG. 10 is a diagram showing another exemplary operation of an imageprocessing unit according to a first preferred embodiment;

FIG. 11 is a diagram showing a yet another exemplary operation of animage processing unit according to a first preferred embodiment;

FIG. 12 is a diagram showing a yet another exemplary operation of animage processing unit according to a first preferred embodiment;

FIG. 13 is a diagram showing a yet another exemplary operation of animage processing unit according to a first preferred embodiment;

FIG. 14 is a diagram showing a yet another exemplary operation of animage processing unit according to a first preferred embodiment;

FIG. 15 is a diagram showing a yet another exemplary operation of animage processing unit according to a first preferred embodiment;

FIG. 16 is a diagram showing an exemplary operation of an imageprocessing unit according to a second preferred embodiment;

FIG. 17 is a diagram showing, a specific example of the exemplaryoperation of the image processing unit described with reference to FIG.16;

FIG. 18 is a diagram showing an exemplary control for an SLM performedin accordance with the frame signal of an output video signal generatedin the exemplary operation described with reference to FIG. 16;

FIG. 19 is a second diagram showing an exemplary control for an SLMperformed in accordance with the frame signal of an output video signalgenerated in the exemplary operation described with reference to FIG.16;

FIG. 20 is a diagram showing another exemplary operation of an imageprocessing unit according to a second preferred embodiment;

FIG. 21 is a diagram showing yet another exemplary operation of an imageprocessing unit according to a second preferred embodiment;

FIG. 22 is a diagram showing yet another exemplary operation of an imageprocessing unit according to a second preferred embodiment;

FIG. 23 is a diagram showing yet another exemplary operation of an imageprocessing unit according to a second preferred embodiment;

FIG. 24 is a diagram showing an exemplary operation of an imageprocessing unit according to a third preferred embodiment;

FIG. 25 is a diagram showing a specific example of the exemplaryoperation shown in FIG. 24;

FIG. 26 is a diagram showing another exemplary operation of an imageprocessing unit according to a third preferred embodiment;

FIG. 27 is a diagram showing yet another exemplary operation of an imageprocessing unit according to a third preferred embodiment;

FIG. 28 is a diagram showing yet another exemplary operation of an imageprocessing unit according to a third preferred embodiment;

FIG. 29 is a diagram showing yet another exemplary operation of an imageprocessing unit according to a third preferred embodiment;

FIG. 30 is a diagram showing an exemplary modification of the exemplaryoperation shown in FIG. 29;

FIG. 31 is a diagram showing yet another exemplary operation of an imageprocessing unit according to a third preferred embodiment;

FIG. 32 is a diagram showing an exemplary modification of the exemplaryoperation shown in FIG. 31;

FIG. 33 is a diagram showing an exemplary emission of a variable lightsource according to a third preferred embodiment;

FIG. 34 is a diagram showing an exemplary modification of the exemplaryemission shown in FIG. 33.

FIG. 35 is a diagram showing another exemplary emission of a variablelight source according to a third preferred embodiment;

FIG. 36 is a diagram showing an exemplary operation of a video displaysystem according to a fourth preferred embodiment;

FIG. 37 is a diagram showing a specific example of a method of settingthe weight of intensity per unit of the second control at two times theweight of the intensity per unit of the first control, in the exampleshown in FIG. 36;

FIG. 38 is a diagram showing another specific example of a method ofsetting the weight of intensity per unit of the second control at twotimes the weight of the intensity per unit of the first control;

FIG. 39 is a diagram showing an example of providing a period fordisplaying the sub-frame video image of each color of a plurality ofprimary and complementary colors within the period of one frame of anoutput video signal;

FIG. 40 is a second diagram showing an example of providing a period fordisplaying the sub-frame video image of each color of a plurality ofprimary and complementary colors within the period of one frame of anoutput video signal;

FIG. 41 is a third diagram showing an example of providing a period fordisplaying the sub-frame video image of each color of a plurality ofprimary and complementary colors within the period of one frame of anoutput video signal;

FIG. 42 is a fourth diagram showing an example of providing a period fordisplaying the sub-frame video image of each color of a plurality ofprimary and complementary colors within the period of one frame of anoutput video signal;

FIG. 43 is a fifth diagram showing an example of providing a period fordisplaying the sub-frame video image of each color of a plurality ofprimary and complementary colors within the period of one frame of anoutput video signal;

FIG. 44 is a functional block diagram showing an exemplary configurationof a video display system using a color wheel;

FIGS. 45A, 45B, 45C and 45D are diagrams showing different perspectiveviews of an exemplary configuration of the optical comprisal of atwo-panel video display system;

FIG. 46 is a functional block diagram showing an exemplary configurationof a circuit for a video display system including the optical comprisalshown in FIGS. 45A, 45B, 45C and 45D;

FIG. 47 is a diagram showing an exemplary configuration of a two-panelvideo display system using a color wheel;

FIG. 48 is a chart showing the intensity of projection light obtained inthe ON state of a micromirror;

FIG. 49 is a chart showing the intensity of projection light obtained inthe OFF state of a micromirror;

FIG. 50 is a chart showing the intensity of projection light obtained inthe oscillation state of a micromirror;

FIG. 51 is a chart exemplifying a pulse width modulation (PWM) usingbinary data;

FIG. 52 is a chart exemplifying a conversion of binary data intonon-binary data;

FIG. 53 is a chart exemplifying a conversion of a part of binary datainto non-binary data;

FIG. 54 is a chart exemplifying a conversion of binary data intonon-binary data in a display system according to a preferred embodimentof the present invention;

FIG. 55 is a diagram showing another exemplary operation of a videodisplay system according to a fourth preferred embodiment; and

FIG. 56 is a diagram showing a specific example of a method for settingthe weight of the intensity per unit of the second control at 1.5 timesthe weight of the intensity per unit of the first control, in theexample shown in FIG. 55.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments according to the present invention are describedbelow with reference to the accompanying drawings.

First Preferred Embodiment

FIG. 4 is a diagram showing an exemplary configuration of a videodisplay system according to a preferred embodiment of the presentinvention.

As shown in FIG. 4, the video display system 1001 includes one spatiallight modulator (SLM) 1002, a total internal reflection (TIR) prism1003, a projection optical system 1004, a light source optical system1005, a display processing unit 1006, and frame memory 1007.

The SLM 1002 and TIR-prism 1003 are place in the optical axis of theprojection optical system 1004, and the light source optical system 1005is placed in such a manner that its optical axis is aligned with that ofthe projection optical system 1004.

The TIR prism 1003 causes an illumination light 1008, incoming from thelight source optical system 1005 placed onto the side, to enter the SLM1002 at a prescribed inclination angle as incident light 1009 and causesa reflection light 1010, reflected by the SLM 1002, to transmit to theprojection optical system 1004.

The projection optical system 1004 projects the reflection light 1010,incoming by way of the SLM 1002 and TIR prism 1003, as projection light5603 onto a screen 1012 or the like.

The light source optical system 1005 comprises a variable light source1013 for generating the illumination light 1008, a first condenser lens1014 for focusing the illumination light 1008, a rod type condenser body1015, and a second condenser lens 1016.

The variable light source 1013, first condenser lens 1014, rod typecondenser body 1015, and second condenser lens 1016 are sequentiallyplaced in the aforementioned order in the optical axis of theillumination light 1008 emitted from the variable light source 1013.

The variable light source 1013 includes a red (R) semiconductor lightsource, a green (G) semiconductor light source, and a blue (B)semiconductor light source (not shown in the drawing), which allowindependent controls for the light emission states. More specifically,the semiconductor light source may employ a laser light source, a lightemitting diode (LED), or the like. Here, the assumption is that a laserlight source is employed. Therefore, the R, G and B laser lights may beused as the illumination light 1008 by controlling the R, G and B laserlight sources to emit light. Additionally, a synthesized lightconstituted by two or more of the three laser light sources R, G and Bmay be used as the illumination light 1008. For example, theillumination light 1008 can be changed to a white light by causing thethree laser light sources R, G and B to emit light simultaneously.Further, the R, G or B laser light source may be controlled to emitlight sequentially, or two or more of the three laser light sources R, Gand B may be caused to emit light sequentially. With such controls, thevideo display system 1001 is enabled not only to carry out amonochromatic display but also to carry out a color display on thescreen 1012 by means of a color sequential method using one SLM 1002.When performing a color display, an operation is carried out in whichone frame of display data is divided into three sub-frames correspondingto each of the colors R, G and B, and the respective laser light sourcesR, G and B are controlled to emit light sequentially in the periodcorresponding to a sub-frame of each color.

The display processing unit 1006 includes an image processing unit(Image Signal Processor) 1017 for processing a continuously inputtedvideo signal 1020, SLM controller 1018 for controlling the SLM 1002, anda light source controller 1019 for controlling the variable light source1013.

The frame memory 1007 is memory used for temporarily storing the data ofan input video signal in the amount of at least one frame. The framememory 1007 is also used as working memory for the image processing unit1017.

FIG. 5 is a functional block diagram showing an exemplary circuitconfiguration of the video display system 1001.

As shown in FIG. 5, the image processing unit 1017 includes an ADconverter 1031, a scaling unit 1032, a frame interpolation unit 1033,and a signal conversion unit (Signal Converter) 1034.

The AD converter 1031 converts an analog signal into the digital signalif the continuously inputted video signal 1020 is the analog signal, andoutputs the post-conversion signal.

If the resolution of the continuously inputted video signal 1020 isdifferent from that of the video display system 1001, and if a videosignal which is a digital signal output from the AD converter 1031 is adigital signal or if the continuously inputted video signal 1020 is adigital signal, the scaling unit 1032 applies a scaling process to thesignal, thereby converting the resolution of the inputted video signal1020 into the resolution of the video display system 1001, and outputsthe post-conversion signal.

The frame interpolation unit 1033 performs a process in accordance witha control signal outputted from a sequencer 1035 (which is describedlater) and, when the resolution of a video signal output from thescaling unit 1032 or the resolution of a video signal output from the ADconverter 1031 is the same as the resolution of the video display system1001, the frame interpolation unit 1033 generates, from the videosignal, a video signal having a higher frame rate than that of the videosignal 1020 and outputs the generated video signal. When thecontinuously inputted video signal 1020 is a digital signal and theresolution of the video signal 1020 is the same as that of the videodisplay system 1001, the frame interpolation unit 1033 generates, fromthe video signal, a video signal having a higher frame rate than that ofthe video signal 1020 and outputs the generated video signal.

The frame interpolation unit 1033, however, carries out the processingso that the data volume for each frame of the video signal to beoutputted is smaller than the data volume per frame of the video signalinput into the frame interpolation unit 1033. Here, the data volume maybe related to the gray scale of an image and/or to the number of pixels.

More specifically, the video signal of a portion of the high frame ratevideo signal generated by the frame interpolation unit 1033 is generatedfrom the video signals of a plurality of frames of the video signalinput into the frame interpolation unit 1033 by means of a motion imageinterpolation. This method detects a moving portion of a video imagefrom the continuously inputted video signal and generates a new videosignal of a frame so as to interpolate the motion. The method ofgenerating a video signal of an interpolation frame determines theintensity of each pixel constituting a video image of a frame to beinterpolated on the basis of a change in the intensity information ofeach pixel constituting continuously inputted video signal.

Furthermore, the frame interpolation unit 1033 generates and outputs aframe synchronous signal (sync) in accordance with the generated highframe rate video signal.

The signal conversion unit 1034 converts, on an as-required basis, thevideo signal output from the frame interpolation unit 1033 into aplurality of sub-frame video signals having the color data of at leastone color from among red (R), green, (G), blue (B), cyan (C), magenta(M), yellow (Y), white (W), black (K) and gray (Gy), and outputs thepost-conversion video signals. This operation makes it possible toconvert, on an as-required basis, a video signal sent from the frameinterpolation unit 1033 into various video signals (i.e., the videosignals of a plurality of sub-frames having the color data of the colorsR, G and B, those of a plurality of sub-frames having the color data ofthe colors R, G, B and W, and those of a plurality of sub-frames havingthe color data of the colors R, G, B, C, M and Y) when a color videoimage is displayed. Further, when, for example, a monochromatic videoimage is displayed, the above described operation makes it possible toconvert a video signal from the frame interpolation unit 1033 into thevideo image of a frame having the color data of no less than one colorfrom among the respective colors W, K and gray (Gy), on an as-requiredbasis.

When the form of a signal to be outputted is configured to be the videosignals of a plurality of sub-frames having the color data of R, G andB, the signal conversion unit 1034 outputs the video signals of therespective sub-frames of the inputted video signal, as is, to alater-stage circuit if the form of the input signal and that of a signalto be outputted are identical, such as when the form of the input signalhas the data of the colors R, G and B. Further, if the video signal 1020is a YUV signal and if a monochromatic video image is to be displayed,the signal conversion unit 1034 outputs a Y signal, as is, expressingthe intensity of the inputted video signal, to a later-stage circuit.

The SLM controller 1018 includes a sequencer 1035 and an image formatter1036.

The sequencer 1035 controls the frame interpolation unit 1033 and alsocontrols the operational timings of the image formatter 1036, SLM 1002,and light source controller 1019 in accordance with a frame synchronoussignal which is outputted from the frame interpolation unit 1033.

The image formatter 1036 generates display-use data (Video Data) 1046for the SLM 1002 from the signal of the frame (noted as “frame signal”hereinafter) of a video signal output from the signal conversion unit1034 and outputs the generated data. For example, when a color videoimage is to be displayed, and when a video signal having the color dataof each of the colors R, G and B is inputted, the image formatter 1036generates the video signals for the R-, G- and B-use sub-framescorresponding to the video images of the inputted frames as the videodata for the SLM 1002, and outputs the generated video signals in a timesequence. Further, when, for example a monochromatic video image is tobe displayed, and when a video signal constituted by frame signalshaving the color data of at least one color of the colors W, K and gray(Gy) (or a video signal which is a YUV signal) is inputted, the imageformatter 1036 generates a monochrome-use video signal corresponding tothe inputted video signals of the respective frames as the video datafor the SLM 1002, and outputs the generated video signal.

The SLM 1002 is connected to the SLM controller 1018 by way of atransmission path compliant with a Low-Voltage Differential Signaling(LVDS) Standard, and includes a timing controller 1041, a latch circuit1042, a Column driver 1043, a Row driver 1044, and a pixel element array1045, in which a plurality of pixel elements is placed in an array(noted as “arrayed” hereinafter).

The timing controller 1041 controls the operational timings of the latchcircuit 1042, Column driver 1043, and Row driver 1044, in accordancewith a timing signal (Address data Clock) 1047 which is outputted fromthe sequencer 1035.

The latch circuit 1042 retains the video data, which is outputted fromthe image formatter 1036 temporarily, and supplies the Column driver1043 with the video data.

The individual pixel elements of the pixel element array 1045 are drivenby the operations of the Column driver 1043 and Row driver 1044.

FIG. 6 is a diagram showing the configuration of an SLM 1002 in furtherdetail.

Referring to FIG. 6, the above described latch circuit 1042 is shown asa selector. Further, the Column driver 1043 is shown as a plurality ofColumn drivers. Timing signals inputted into the timing controller 1041are shown as Digital control signals. The transmission line for thevideo data inputted into the latch circuit 1042 is shown as n data bus.The individual pixel element includes a memory cell, as described laterin detail, and therefore the pixel element array 1045 is also defined asincluding a memory array in which a plurality of memory cells isarrayed.

As shown in FIG. 6, a plurality of pixel elements is placed in a gridpattern at the positions where individual bit lines, extendingvertically from the Column driver 1043, cross individual word lines,extending horizontally from the Row driver 1044, in the pixel elementarray 1045.

FIG. 7 is a cross-sectional diagram showing an exemplary configurationof an individual pixel element.

As shown in FIG. 7, an individual pixel element includes a deflectablemirror 1053 supported on a substrate 1051 by an elastic hinge 1052. Themirror 1053 is covered with a cover glass 1054 for protection.

The mirror 1053 is connected to the ground (GND) potential or a specificpotential by way of the elastic hinge 1052 and substrate 1051.

An OFF electrode 1055 and an ON electrode 1057 are placed symmetricallyacross the elastic hinge 1052 on the substrate 1051, and likewise an OFFstopper 1056 and an ON stopper 1058 are placed on the substrate 1051.

When a predetermined voltage is applied to the OFF electrode 1055, itattracts the mirror 1053 with a Coulomb force generated between themirror and the OFF electrode 1055 so as to tilt the mirror 1053 to aposition abutting the OFF stopper 1056. This causes the incident light1059 to be reflected by the mirror 1053 to the OFF light path 1060,which is shifted away from the optical axis of the projection opticalsystem 1004. The state of the mirror 1053 in this position is known asthe OFF state.

When a predetermined voltage is applied to the ON electrode 1057, itattracts the mirror 1053 with a Coulomb force generated between themirror and the ON electrode 1057 so as to tilt the mirror 1053 to aposition abutting the ON stopper 1058. This causes the incident light1059 to be reflected by the mirror 1053 to the ON light path 1061, whichis aligned with the optical axis of the projection optical system 1004.The state of the mirror 1053 in this position is known as the ON state.

By stopping the application of a voltage to the OFF electrode 1055 (orthe ON electrode 1057) when the mirror 1053 is tilted in a positionabutting the OFF stopper 1056 (or the ON stopper 1058), the Coulombforce generated between the mirror 1053 and the OFF electrode 1055 (orthe ON electrode 1057) is eliminated, causing the mirror 1053 tooscillate freely in accordance with the elasticity of the elastic hinge1052. During the free oscillation, the incident light 1059 is reflectedby the mirror 1053 to a light path between the OFF light path 1060 andthe ON light path 1061. The state of the mirror 1053 in this position isknown as an oscillation state. More specifically, the total intensity oflight (also noted as “light intensity” hereinafter) reflected towardsthe projection optical system 1004 by the mirror performing the freeoscillation is lesser than the light intensity when the mirror 1053 isin the ON state and is greater than the light intensity when the mirror1053 is in the OFF state. That is, it is possible to set the lightintensity between the light intensities of the ON state and OFF state.

FIGS. 48, 49 and 50 show the intensity of light projected by theprojection optical system 1004 when the mirror 1053 is in the ON state,OFF state and oscillation state, respectively.

FIG. 8 is a diagram showing an exemplary configuration of the circuitfor an individual pixel element.

As shown in FIG. 8, an OFF capacitor 1055 b is connected to the OFFelectrode 1055, and the OFF capacitor 1055 b is connected to a bit line1071-1 and a word line 1072 by way of a gate transistor 1055 c. Here,the OFF capacitor 1055 b and gate transistor 1055 c constitute aDRAM-structured memory cell.

Further, an ON capacitor 1057 b is connected to the ON electrode 1057,and the ON capacitor 1057 b is connected to a bit line 1071-2 and a wordline 1072 by way of a gate transistor 1057 c. Here, the ON capacitor1057 b and gate transistor 1057 c constitute a DRAM-structured memorycell.

The opening and closing of the gate transistor 1055 c and gatetransistor 1057 c are controlled by the word line 1072.

Specifically, a single horizontal row of the pixel elements in line withan arbitrary word line 1072 are simultaneously selected, and thecharging and discharging of capacitance to and from the OFF capacitor1055 b and ON capacitor 1057 b are controlled by way of the bit lines1071-1 and 1071-2, and thereby the individual ON/OFF and oscillationcontrols for the mirrors 1053 in the pixel units within a singlehorizontal row are carried out.

At this point, a description is provided for binary data and non-binarydata with reference to FIGS. 51, 52, 53 and 54.

As shown in FIG. 51, the N bits of binary data (i.e., a binary videosignal 400) are data which have different weights from the leastsignificant bit (LSB) to the most significant bit (MSB).

When a gray scale is represented by means of a pulse width modulation(PWM), the weight of each bit expresses a length of time for performinga pulse control, that is, the period of an ON state of each segment(i.e., a sub-frame).

The example shown in FIG. 52 is an embodiment in which the entire 5 bitsof input binary data is converted into non-binary data with “weight”=1.

For data of the entire 5 bits of the binary data, the period of asegment (i.e., a sub-frame) is determined with the weight (i.e.,weight=1) of the LSB, the data is converted into non-binary data (i.e.,a bit string) for each segment and is transferred to the spatial lightmodulator 1002.

Specifically, the number of times the ON state appears in the LSBinterval of the binary data is calculated and a gray scale isrepresented so that the period of an ON state continues for the durationof the bit string.

Meanwhile, the example shown in FIG. 53 is an embodiment in which theintermediate 3 bits of binary data is converted into non-binary data.The example also shows a case in which the least significant bit (LSB)of the binary data is subjected to a light intensity modulation (at theratio of light intensity=1/2) by means of the spatial light modulator1002 or variable light source 1013. In this case, the weight of allbits, other than the most significant bit (MSB), of the binary data is“2” to extend the interval of one segment, and thereby the interval ofthe LSB segment is lined up with the intervals of other segments.

The individual pixel element (i.e., the pixel unit 1045) of the spatiallight modulator 1002 is a micromirror 1053 which is controlled under anyof the states including the ON/OFF (positioning) state, oscillatingstate and intermediate state.

As shown in FIG. 54, the present embodiment is configured to control theON/OFF (positioning) state and oscillating state with display-use data(video data) 1046 outputted from the image formatter 1036 and with atiming signal (address data clock) 1047 which is outputted from thesequencer 1035.

What follows is a description of an exemplary operation of the imageprocessing unit 1017 comprised in the display processing unit 1006, asan exemplary operation related to the present embodiment in the videodisplay system 1001, with reference to FIGS. 9 through 15.

In each of the FIGS. 9 through 15, “input video signal,” shown in theupper half, represents a video signal which is inputted into the frameinterpolation unit 1033, and “output video signal,” shown in the lowerhalf, represents a video signal which is outputted from the signalconversion unit 1034.

Assuming that a video signal 1020 continuously inputted into the imageprocessing unit 1017 is a digital signal and also that the resolution ofthe input signal is the same as that of the video display system 1001,the “input video signal” shown in the upper half of the figureconstitutes a video signal 1020. Further, in each of the FIGS. 9 through15, the video image of the “input video signal” shown in the upper halfis an image of a ball moving from the bottom left to the top right.

FIG. 9 is a diagram showing an exemplary operation of the imageprocessing unit 1017.

FIG. 9 exemplifies the case of generating, from an input video signalwhich has a 120 Hz frame rate and in which the video signal of eachframe has 10-bit gray scale data for each pixel, an output video signalwhich has a 240 Hz frame rate and in which the video signal of eachframe has 9-bit gray scale data for each pixel.

In the present example, an output video signal generated within theperiod of one frame of an input video signal consists of signals of twoframes, i.e., the video signal of the first frame of an output videoimage, which is the video signal generated by converting the gray scaledata, 10-bit data, of the video signal of the first frame of an inputvideo image for each pixel into 9-bit data, and the video signal of thesecond frame of an output video image, which is the video signalgenerated from the video signals of the two adjacent frames of the inputvideo image, specifically, the video signals of the first and secondframes of the input video image generated by a motion imageinterpolation which has 9-bit gray scale data for each pixel.

In the present example, since the video signal of each frame of theinput video image has 10-bit gray scale data for each pixel and thevideo signal of each frame of the output video image has 9-bit grayscale data for each pixel, the data volume of the gray scale data of thevideo signal of each frame of the output video image for each pixel isone half (=2⁹/2¹⁰) of the corresponding data volume of the input videoimage. The data volume related to the gray scale data for each videosignal of one frame of an output video image is one half (“fra 1/2”) ofthe corresponding data volume of the input video image.

Furthermore, in the present example, the frame rate of the input videosignal is 120 Hz, while the frame rate of the output video signal is 240Hz, and therefore, the output video signal has a frame rate two timesthat of the input video signal.

Since the output video signal has a gray scale data volume one-half thatof the input video signal, with the frame rate two times that of theinput video signal, it is possible to generate an output video signal attwo times the frame rate of the input video signal without the need tochange the data volume for the period of one frame of the input videosignal.

FIG. 10 is a diagram showing another exemplary operation of the imageprocessing unit 1017.

FIG. 10 exemplifies the case of generating, from an input video signalwhich has a 60 Hz frame rate and in which the video signal of each framehas 10-bit gray scale data for each pixel, an output video signal whichhas a 480 Hz frame rate and in which the video signal of each frame has7-bit gray scale data for each pixel.

In this example, an output video signal generated in the period of oneframe of an input video signal consists of signals of eight frames,specifically, the video signal of the first frame of an output videoimage, which is the video signal generated by converting the 10-bit dataof the video image of the first frame into 7-bit data, and the sevenvideo signals of the 2nd through 8th frames of the output video image,which are generated from the video signals of the first frame and secondframe of the input video image, by means of a motion image interpolationand which have 7-bit gray scale data for each pixel.

In the present example, since the video signal of each frame of theinput video image has 10-bit gray scale data for each pixel and thevideo signal of each frame of the output video image has 7-bit grayscale data for each pixel, the data volume of the gray scale data, perpixel of the video signal of each frame of the output video image, isone eighth (“⅛”) (=2⁷/2¹⁰) of the corresponding data volume of the inputvideo image. The data volume related to the gray scale data for oneframe of an output video image is one eighth (⅛) of the correspondingdata volume of the input video image.

Further, in the present example, the frame rate of the input videosignal is 60 Hz, while the frame rate of the output video signal is 480Hz, and therefore the output video signal has a frame rate eight times(8×) that of the input video signal.

Since, the output video signal has a gray scale data volume one eighth(⅛) that of the input video signal, with a frame rate of eight times(8×) that of the input video signal, it is possible to generate anoutput video signal at eight times the frame rate of the input videosignal without the need to change the data volume for the period of oneframe of the input video signal.

More specifically, the exemplary operations shown in FIGS. 9 and 10exemplifies the case of generating a video signal output at higher framerates, respectively, two times and eight times the frame rate of thevideo signal 1020 inputted. It is likewise possible to generate anoutput video signal which has a higher frame rate ranging from two timesto eight times the frame rate of the video signal 1020.

Also More specifically, the exemplary operations shown in FIGS. 9 and 10exemplify the cases in which the gray scale data volume for each videosignal of one frame of the output video image are, respectively, ½ and ⅛of the corresponding data volume of the input video signal. It islikewise possible to designate a gray scale data volume for each videosignal of one frame of the output video image to range from ½ to ⅛ ofthe corresponding data volume of the input video signal.

FIG. 11 is a diagram showing yet another exemplary operation of theimage processing unit 1017.

FIG. 11 exemplifies the case of generating, from an input video signalwhich has a 60 Hz frame rate and in which the video signal of each framehas 10-bit gray scale data for each pixel, an output video signal whichhas a 180 Hz frame rate and in which the video signal of each frame has9-bit gray scale data for each pixel. In this case, however, the videosignal of each frame is generated such that in two out of three frames(i.e., the second and third frames) of the output video signal generatedwithin the period of one frame of the input video signal, the pixels onthe odd-numbered lines are thinned out from the video signal of oneframe and the pixels on the even-numbered lines are thinned out from thevideo signal of the other frame.

In the present example, the output video signal generated within theperiod of one frame of the input video signal consists of signals ofthree frames: the video signal of the first frame of the output videoimage, which is the video signal generated by converting the 10-bit dataof the video signal of the first frame of an input video signal for eachpixel into 9-bit data, and the video signals of the second frame andthird frame of the output video image, which are obtained by generatingthe video signal of the two frames having 9-bit gray scale data for eachpixel from the video signals of the adjacent first frame and secondframe of the input video image. These frames are generated by means of amotion image interpolation, thinning out the pixels on the odd-numberedlines from the video signal of one of the two frames having 9-bit grayscale data and thinning out the pixels on the even-numbered lines fromthe video signal of the other frame. More specifically, in this case,the number of pixel lines of each of the video signals of the two framesis smaller than the number of pixel lines of the input video signal.

In the present example, the input video signal has 10-bit gray scaledata for each pixel and the video signal of the first frame of theoutput video image has 9-bit gray scale data for each pixel in theperiod of one frame of the input video signal. Therefore, the datavolume of the gray scale data of the video signal of the first frame foreach pixel is one-half (“½”) (=2⁹/2¹⁰) of the corresponding data volumeof the video signal of the first frame of the input video signal.Further, each of the video signals of the second and third frames of theoutput video signal has 9-bit gray scale data for each pixel, and thepixels on the odd-numbered lines or even-numbered lines are thinned out,and therefore, the gray scale data volume of each of the video signalsof the second and third frames is a quarter (“¼”) (=2⁹/2¹⁰/2) of thecorresponding data volume of the input video signal.

Furthermore, in the present example, the frame rate of the input videosignal is 60 Hz, while that of the output video signal is 180 Hz, andtherefore, the output video signal has a frame rate three times that ofthe input video signal.

As such, the gray scale data volume of the video signal of the firstframe of the output video signal is ½ of the corresponding data volumeof the input video signal, and the gray scale data volume of each of thevideo signals of the second and third frame of the output video signalis ¼ of the corresponding data volume of the input video signal in theperiod of one frame of the input video signal, and furthermore, theframe rate of the output video signal is three times that of the inputvideo signal. Thereby it is possible to generate an output video signalwith a frame rate three times that of the input video signal without aneed to change a data volume for the period of one frame of the inputvideo signal.

More specifically, if the SLM 1002 is controlled on the basis of a framesignal produced by thinning out the pixels on the odd-numbered oreven-numbered lines of an output video signal, the mirror 1053 of thepixel element corresponding to the thinned out pixel is controlled underthe OFF state.

FIG. 12 is a diagram showing yet another exemplary operation of theimage processing unit 1017.

FIG. 12 exemplifies the case of generating, from an input video signalwhich has a 60 Hz frame rate and the video signal of each frame has10-bit gray scale data for each pixel, an output video signal which hasa 180 Hz frame rate and in which the video signal of each frame has9-bit gray scale data for each pixel. In this case, however, the videosignal of each frame is generated such that, of the video signals of thesecond and third frames, from among three frames of output video signalgenerated within the period of one frame of the input video signal, thepixels in the odd-numbered columns of the odd-numbered lines and thepixels in the even-numbered columns of the even-numbered lines arethinned out from the video signal of one frame (of the aforementionedtwo frames), while the pixels in the even-numbered columns of theodd-numbered lines and the pixels in the odd-numbered columns of theeven-numbered lines are thinned out from the video signal of the otherframe.

In the present example, the output video signal generated within oneframe of the input video signal consists of signals of three frames,i.e., the video signal of the first frame of the output video image,generated by converting the 10-bit data of the video signal of the firstframe of the input video signal for each pixel into 9-bit data, and thevideo signals of the second and third frame of the output video image,which are obtained by generating the video signals of the two frameshaving 9-bit gray scale data for each pixel from the video signals ofthe adjacent first and second frame of the input video image. Theseframes are generated by means of a motion image interpolation, thinningout the pixels in the odd-numbered columns of the odd-numbered lines andthe pixels in the even-numbered columns of the even-numbered lines fromthe video signal of one frame (of the aforementioned two frames having9-bit gray scale data), and thinning out the pixels in the even-numberedcolumns of the odd-numbered lines and the pixels in the odd-numberedcolumns of the even-numbered lines from the video signal of the otherframe.

In the present example, the video signal of the frame of the input videoimage has 10-bit gray scale data for each pixel, and the video signal ofthe first frame of the output video image has 9-bit gray scale data foreach pixel in the period of one frame of the input video signal.Therefore the volume of the gray scale data of the video signal of thefirst frame for each pixel of is one-half (½) (=2⁹/2¹⁰) of thecorresponding volume of the video signal of the frame of the input videoimage. Specifically, the gray scale data volume of the video signal ofthe first frame of the output video signal is one-half of thecorresponding data volume of the video signal of the frame of the inputvideo image. Further, the video signal of each of the second and thirdframes of the output video signal has 9-bit gray scale data for eachpixel. Also the pixels in the odd-numbered columns of the odd-numberedlines and the pixels in the even-numbered columns of the even-numberedlines, or the pixels in the even-numbered columns of the odd-numberedlines and the pixels in the odd-numbered columns of the even-numberedlines, are thinned out. Therefore the gray scale data volume of each ofthe video signals of the two frames, i.e., the second and third frames,is a quarter (“¼”) (=2⁹/2¹⁰/2) of the corresponding data volume of thevideo signal of the frame of the input video image.

Further in the present example, the frame rate of the input video signalis 60 Hz, while that of the output video signal is 180 Hz, and thereforethe output video signal has a frame rate which is three times that ofthe input video signal.

As such, the gray scale data volume of the video signal of the firstframe of the output video image is ½ of the corresponding data volume ofthe video signal of the frame of the input video image, and the grayscale data volume of each of the video signals of two frames, i.e., thesecond and third frames, of the output video image is a quarter (“¼”) ofthe corresponding data volume of the video signal of the frame of theinput video image. Furthermore, the frame rate of the output videosignal is three times that of the input video signal in the period ofone frame of the input video signal. Thereby it is possible to generatean output video signal with a frame rate three times that of the inputvideo signal without a need to change the data volume for each period ofone frame of the input video signal.

More specifically, if the SLM 1002 is controlled on the basis of thevideo signal of the frame of an output video signal, in which the pixelsin the odd-numbered columns of the odd-numbered lines and the pixels inthe even-numbered columns of the even-numbered lines, or the pixels inthe even-numbered columns of the odd-numbered lines and the pixels inthe odd-numbered columns of the even-numbered lines, are thinned out,the mirror 1053 of a pixel element corresponding to the thinned outpixel is controlled under the OFF state.

FIGS. 13 and 14 are diagrams showing yet another exemplary operation ofthe image processing unit 1017.

FIGS. 13 and 14 illustrate the process of generating an output videosignal which has a 180 Hz frame rate from an input video signal whichhas a 60 Hz frame rate and in which the video signal of each frame has10-bit gray scale data for each pixel. In this case, however, the videosignal of a frame is generated such that, of the video signals of threeframes of an output video image are generated within the period of oneframe of the input video signal, each of the video signals of the firstand second frames has 9-bit gray scale data for each pixel, and suchthat the video signal of the third frame has only grayscale designationdata designating all pixels to be white (W), black (K) or gray (Gy).

In the present example, the output video signal generated within theperiod of one frame of the input video signal consists of signals ofthree frames, i.e., the video signal of the first frame of an outputvideo image, which is the video signal generated by converting 10-bitdata of the video signal of the first frame of an input video signal foreach pixel into 9-bit data, the video signal of the second frame of anoutput video signal having 9-bit gray scale data for each pixelgenerated from the video signals of the adjacent first and second framesof the input video image by means of a motion image interpolation, andthe video signal of the third frame of output video image having onlygrayscale designation data designating all pixels to be white (W), black(K) or gray (Gy).

Specifically, the grayscale designation data is generated by the frameinterpolation unit 1033. If the SLM 1002 is controlled on the basis of asignal having only the grayscale designation data, the mirrors 1053 ofall of the pixel elements are likewise controlled so that all pixels aredisplayed in white, black or gray on the basis of the grayscaledesignation data.

FIG. 13 exemplifies the case of applying data so as to designate a grayscale in which all pixels are white. This example makes it possible toobtain a bright video image with less degradation in the contrast.

FIG. 14 illustrates the process of applying data to designate a grayscale in which all pixels are gray. In this example, a gray scale whichdesignates all pixels to be gray can be determined on the basis of theaverage value of intensity of the entire video image in a continuouslyinputted video signal.

As described above, the load related to the generation processing of thevideo signal of a frame can be alleviated by designating one of thevideo signals of the three frames of output video signals as the signalof a frame having only grayscale designation data.

Further, the gray scale data volume of the signal of a frame having onlythe grayscale designation data is limited to a data volume required todesignate a gray scale common to all pixels, significantly reducing thedata volume when compared with the data volume of another frame of anoutput video image. Therefore, the present example also makes itpossible to generate an output video signal having a frame rate threetimes that of the input video signal without a need to change the datavolume related to the gray scale data for the period of one frame of theinput video signal.

FIG. 15 is a diagram that shows yet another exemplary operation of theimage processing unit 1017.

The image processing unit 1017 used for the present exemplary operationsimilar to a unit included in the existing image processing system thatwas described for FIG. 2, has a processing capability of generating,from an input video signal which has a 60 Hz frame rate and in whicheach pixel has 10-bit data, an output video signal which has a 120 Hzframe rate and in which each pixel has 10-bit gray scale data.Specifically, the image processing unit 1017 used for the presentexemplary operation includes a frame interpolation unit 1033 having adata processing capability of approximately two times the imageinterpolation process shown in the systems shown in FIGS. 9 through 14.

FIG. 15 exemplifies the case of generating an output video signal whichhas a 360 Hz frame rate from an input signal which has a 60 Hz framerate and in which the video signal of each frame has 10-bit gray scaledata for each pixel. In this case, however, an output video signal isgenerated such that, of the video signals of six frames of an outputvideo image generated within one frame of the input video signal, eachof the video signals of the first, second, fourth and fifth frames has9-bit gray scale data for each pixel, and such that each of the videosignals of the remaining two frames, the third and sixth frames, has2-bit gray scale data for each pixel.

In the present example, an output video signal generated within theperiod of one frame of the input video signal consists of signals of sixframes, i.e., the video signal generated by converting the gray scaledata of the video image of the first frame of an input video signal foreach pixel, that is, 10-bit data, into 9-bit data, the video signals ofthe second, fourth and fifth frames of the output video image which aregenerated from the video signals of the adjacent first and second framesof the input video image by means of a motion image interpolation andwhich have 9-bit gray scale data for each pixel, and the video signalsof the third and sixth frames of the output video image, which have2-bit gray scale data for each pixel and are generated in a similarmanner to the aforementioned video signals of three frames.

According to the present example, the frame rate of the input videosignal is 60 Hz, while the frame rate of the output video signal is 360Hz. Therefore the output video signal has a frame rate 6 times (6×) thatof the input video signal. However, in contrast to a video signal of aframe of an input video image having 10-bit gray scale data for eachpixel generated within the period of one frame, the video signals of thefirst, second, fourth and fifth frames of the output video image have9-bit gray scale data for each pixel, and the video signals of the thirdand sixth frames have 2-bit gray scale data for each pixel. Thereforethe total gray scale data volume of the output video signal for theperiod of one frame of input video image is a little larger than twotimes that of the input video signal. Such an operation can be carriedout if the video display system 1001 has a high display processingcapability.

Specifically, the present example is configured with each of the videosignals of the third and sixth frames have 2-bit gray scale data foreach pixel. An alternative configuration may be such that theaforementioned video signal has, for example, 1-bit gray scale data foreach pixel. Such a configuration makes it possible to adjust the totalgray scale data volume of the output video signal for the period of oneframe of the input video signal to be closer to two times the datavolume of the input video signal. Specifically, the configuration makesit possible to change the number of gray scales in which the display isperformed to the equivalent of one pixel of the video signals of thethird and sixth frames, in accordance with the processing capability ofan image processing apparatus.

As described above, the present embodiment is configured to generatevideo signals of a plurality of frames of an output video image so thatthe total volume generated within the period of one frame of thecontinuously inputted video signal is the same as the volume of theinput video signal, thereby making it possible to attain a motion imagedisplay with smoother movement without increasing the load of videoimage processing and display processing.

Second Preferred Embodiment

The following is a description of an exemplary operation of the imageprocessing unit 1017 equipped in the display processing unit 1006, SLMcontroller 1018, and spatial light modulator (SLM) 1002, according tothe present embodiment performed in the video display system 1001.

According to the present embodiment, the number of gray scales ofbrightness of each piece of pixel data in the video signal of each framecontinuously outputted from the signal conversion unit 1034 is smallerthan the corresponding number in the video signal of each frame inputtedinto the frame interpolation unit 1033, but in which the imageprocessing unit 1017 and SLM controller 1018 processes the data suchthat the number of gray scales of brightness perceived by an observerviewing the video image is approximately the same as the number of grayscales of brightness of the data in the input video signal 1020.

Further specifically, the image processing unit 1017 generates, from avideo signal which is inputted into the frame interpolation unit 1033,an output video signal in which the gray scale data volume of the videosignal for each frame is smaller than the corresponding data volume ofthe input video signal and which has a higher frame rate than that ofthe input video signal. For a plurality of continuous frames of theoutput video signals generated within the period of one frame of theinput video signal, the SLM controller 1018 predetermines an offsetamount in the level of brightness in other frames relative to a firstframe, which functions as a reference frame. Then, an output videosignal, having a plurality of continuous frames, is generated so thatthe gray scale of brightness of a video image, perceived by an observerviewing and sequentially integrating a plurality of video images, isapproximately equal to the gray scale of brightness of a video imageperceived when viewing the video image in accordance with the framesignal of the input video image.

This operation sets the perceived gray scale of brightness of a videoimage, continuously projected in accordance with the output videosignal, approximately equal to the gray scale of brightness of the videoimage of the input video signal.

FIG. 16 is a diagram showing such an exemplary operation of the imageprocessing unit 1017.

Referring to FIG. 16, more specifically, the label, “input video signal”represents a video signal inputted into the frame interpolation unit1033, and the label, “output video signal” represents a video signaloutputted from the signal conversion unit 1034 (this designation is thesame for FIG. 17 and FIGS. 20 through 23). Assuming that a video signal1020 continuously inputted into the image processing unit 1017 is adigital signal and also that the resolution of the video signal 1020 isthe same as that of the video display system 1001, the “input videosignal” constitutes the video signal 1020. Further, in FIG. 16, thevideo image of the “input video signal” is a video image of a ballmoving from the bottom left to the top right (which is the same for FIG.17 and FIGS. 20 through 23).

FIG. 16 exemplifies the case of generating, from an input video signalwhich has a 60 Hz frame rate and in which the video signal of each framehas 10-bit gray scale data for each pixel, an output video signal whichhas a 120 Hz frame rate and in which the video signal of each frame has9-bit gray scale data for each pixel.

In this example, an output video signal generated within the period ofone frame of an input video signal consists of signals of two frames:1.) the video signal of the first frame, which is generated byconverting the 10-bit data of the video image of the first frame of aninput video image for each pixel into 9-bit data, and 2.) the videosignal of second frame, which is generated from the video signals of theadjacent first and second frames of the input video signal by means of amotion image interpolation, and which has 9-bit gray scale data for eachpixel.

For the output video signals of the two frames, the brightness of adisplay video image determined in accordance with the value (excluding“0”) of gray scale data is set differently for the video signal of thefirst frame than for the second frame. In this example, it ispredetermined that one-half (“½”) of the amount of change of brightnessper gray scale level, which can be expressed by the video signal of thefirst frame, is designated as an offset amount. The gray scale levels(excluding “0”) expressible with the video signal of the second frame iscalculated by adding the offset amount to each of the gray scale levels(excluding “0”) of the first frame. For example, assuming that theamount of change of brightness per gray scale level of the first frameis “1”, the gray scale levels (excluding “0”) of the second frame iscalculated by adding 0.5 (=½), as the offset amount, to each of the grayscale levels (excluding “0”) of the first frame. In this case, the valueof the next higher gray scale level after “0” of the first frame is “1”,and therefore, the next higher gray scale level after “0” of the secondframe is “1.5” (=1+0.5). Likewise, the next higher gray scale levelafter “1” of the first frame is “2”, and therefore, the next higher grayscale level to “1.5” of the second frame is “2.5” (=2+0.5).

By applying the calculations described above, an output video signal,which has two continuous frames per one frame of the input video signal,is generated such that the perceived gray scale of brightness of a videoimage (obtained by the SLM 1002 modulating the illumination light 1008in accordance with the output video signal) is approximately equal tothe perceived gray scale of brightness of a video image obtained by theSLM 1002 modulating the illumination light 1008 in accordance with thevideo image of the input video image.

With this operation, the number of gray scales of brightness expressiblewith the output video signals constituting the two continuous frames is“512” (=9 bits), whereas the number of gray scales of brightnessperceived by the observer, integrating the two continuous video images,is approximately “1024” (=10 bits), which is the number of gray scalesof brightness expressible with the video image projected onto the screen1012 in accordance with the input video signal. Therefore, when aplurality of continuously outputted video images is projected onto ascreen 1012 in accordance with the output video signals, the gray scaleof brightness of perceived by an observer is approximately equal to thegray scale of brightness of the video image of the input video signal.

FIG. 17 is a diagram showing, further specifically, the exemplaryoperation of the image processing unit 1017, SLM controller 1018, andspatial light modulator (SLM) 1002, all of which are described withreference to FIG. 16. The example shown in FIG. 17, however, assumes forthe sake of convenience, that the video signal of each input frame has3-bit gray scale data for each pixel, that the frame rate of the outputvideo signal is two times that of the input video signal, and that theoutput video signal of each frame has 2-bit gray scale data for eachpixel.

As shown in FIG. 17, first, the video signals of two frames,intermediate video signals, are generated within the period of one frameof the input video image. Here, the video signal of the first frame isthe same as the frame signal of the input video signal, and the videosignal of the second frame is a video signal generated from the inputvideo signals of two adjacent frames by means of a motion imageinterpolation. Note that, at this point, the gray scale data of eachframe signal of the intermediate video signal for each pixel remains as3-bit data.

Then, each of the video signals of the first and second frames, with3-bit gray scale data (i.e., the number of gray scales=8) for eachpixel, is converted into an output video signal having 2-bit gray scaledata (i.e., the number of gray scales=4) for each pixel.

In this conversion, one-half (½) of the amount of change of brightnessper gray scale level, expressible with the video signal of thepost-conversion first frame, is designated as an offset amount. Thevalues, obtained by adding the offset amount to each of the gray scalelevels of brightness (excluding “0”) of the post-conversion first frame,are defined as the gray scale levels (excluding “0”) of brightnessexpressible with the video signal of the post-conversion second frame.With this calculation, the conversion is carried out so that the grayscale of brightness of a video image perceived by an observer viewingand integrating two video images, obtained by the SLM 1002 modulatingthe illumination light 1008 in accordance with the video signals of thepost-conversion first and second frames, is approximately equal to thegray scale of brightness perceived by the observer viewing a video imageobtained by the SLM 1002 modulating the illumination light in accordancewith the frame signal of the input video image corresponding to theaforementioned post-conversion frames.

In this example, the video signal of the first frame of the intermediatevideo signal is converted from a signal in which eight gray scale levelvalues (i.e., 0, 1, and 2 through 7) can be expressed with 3-bit grayscale data for each pixel into an output video signal in which the fourgray scale level values (i.e., 0, 2, 4 and 6) can be expressed with2-bit gray scale data for each pixel. The video signal of the secondframe of the intermediate video signal is converted from a signal inwhich eight gray scale level values (i.e., 0, 1, and 2 through 7) can beexpressed with 3-bit gray scale data for each pixel into an output videosignal in which the four gray scale level values (i.e., 0, 3, 5 and 7)can be expressed with 2-bit gray scale data for each pixel. Morespecifically, the gray scale levels expressible with the first framesignal of the output video signal are 0, 2, 4 and 6, and therefore, theoffset value is “1”. Therefore, the gray scale levels expressible withthe second frame signal of the output video signal are 0, 3 (=2+1), 5(=4+1) and 7 (=6+1). As such, the video signal of each frame, after theconversion from an intermediate video signal into an output videosignal, is a result of thinning out a part of the gray scale levelvalues of brightness expressible with units of pixels of thepre-conversion video signal. Also, the video signals of the first andsecond frames of the output video signal differ in the expressible grayscale levels of brightness (excluding “0”).

With this operation, the expressible number of gray scales, projected inaccordance with the output video signals of the generated first andsecond frames, is “4” (=2 bits). The number of gray scales of brightnessperceived by the observer viewing and integrating the video images ofthe two frames is “7” (i.e., 0, 2, 3, 4, 5, 6 and 7) approximately equalto “8” (=3 bits), which is the number of gray scales expressible with avideo image projected onto the screen 1012 in accordance with the inputvideo signal. Therefore, the gray scale perceived by the observer whencontinuous video images are projected onto the screen 1012, inaccordance with the video signals of frames continuously outputted, isapproximately the same as the gray scale of the video image of the inputvideo signal.

More specifically, the present embodiment has been described byexemplifying the case of generating an intermediate video signal fromthe input video signal and providing a processing stage so as togenerate an output video signal from the intermediate video signal. Itis also possible to generate an output video signal directly from theinput video signal so as to obtain a similar output video signal.

FIGS. 18 and 19 are diagrams showing the exemplary controls for the SLM1002 performed in accordance with the output video signal generated inthe exemplary operation described with reference to FIG. 16.

Referring to FIGS. 18 and 19, “first frame” and “second frame” representthe video signals of two continuous frames in an output video signalgenerated within the period of one frame of the input video signal.

As described above, the exemplary operation described with reference toFIG. 16 establishes a rule, in each of the two frames of output videosignals, that one-half (½) of the amount of change of brightness, foreach gray scale level expressible with the first frame signal, isdesignated as the offset amount, and that the values produced by addingthe offset amount to each of the gray scale levels (excluding “0”) ofthe first frame signal are defined as the gray scale levels (excluding“0”) expressible with the second frame signal. Therefore, even if thevalues of 9-bit gray scale data of a specific pixel corresponding to thevideo signals of the two frames are the same, the second frame signalwill be brighter than the first frame by the above described offsetamount, for the specific pixel. Specifically, the light intensityobtained from the second frame signal is higher, by the offset amount,than the light intensity obtained from the first frame signal, for thespecific pixel.

The offset amount is designated as one-half (½) of the amount of changeof brightness for each gray scale level expressible with the first framesignal, and the gray scale data for each pixel of the output videosignal is designated as 9-bit data. Therefore, the light intensitycorresponding to the offset amount is a light intensity which can beobtained by the control on the basis of the gray scale data of ½ LSB ofthe 9-bit.

FIG. 18 exemplifies the case of obtaining a light intensitycorresponding to the offset amount by controlling the mirror 1053 underthe ON state (refer to “½ LSB” of “second frame Mirror state” shown inFIG. 18).

FIG. 19 exemplifies the case of obtaining a light intensitycorresponding to the offset amount by controlling the mirror 1053 underthe oscillation state (refer to “½ LSB” of “second frame Mirror state”shown in FIG. 19).

More specifically, both FIGS. 18 and 19 show exemplary controls for themirror 1053 on the basis of the video signal of the first frame and thesecond frame when the values of gray scale data of a specific pixelcorresponding to the two frames for the period of one frame are same.

Further, in FIGS. 18 and 19, the light intensities are controlled inaccordance with the gray scale data of each pixel for the period of oneframe of an output video signal by combining the ON control, OFFcontrol, and oscillation control of the mirror 1053.

FIG. 20 is a diagram showing another exemplary operation of the imageprocessing unit 1017, SLM controller 1018, and spatial light modulator(SLM) 1002.

FIG. 20 exemplifies the case of generating, from an input video signalwhich has a 60 Hz frame rate and in which each frame signal has 10-bitgray scale data for each pixel, an output video signal which has a 120Hz frame rate and in which the video signal of each frame has 8-bit grayscale data for each pixel.

In the present example, an output video signal, generated within theperiod of one frame of an input video signal, consists of signals ofthree frames, i.e., the video signal of the first frame generated byconverting the gray scale data of the first frame of the input videosignal for each pixel, that is, 10-bit data, into 8-bit data, and thesecond and third frames, which are generated from the first and secondframes of the input video signals by means of a motion imageinterpolation, and which have 8-bit gray scale data for each pixel.

For the three frames of output video signals, a pre-established ruledetermines the level of brightness of display video images on the basisof the value of gray scale data (excluding “0”), which differ among thethree frames of video signals. According to the present example, therule is pre-established so that one-third (⅓) of the amount of change ofbrightness for each gray scale level expressible with the video signalof the first frame is designated as an offset amount. The valuesobtained by adding the offset amount to each of the gray scale levels ofbrightness (excluding “0”) expressible with the video signal of thefirst frame is designated as the gray scale levels of brightness(excluding “0”) expressible with the second frame signal. Similarly, thevalues obtained by adding the offset amount to each of the gray scalelevels of brightness (excluding “0”) expressible with the video signalof the second frame is designated as the gray scale levels of brightness(excluding “0”) expressible with the third frame signal. For example,designating the change of brightness for each gray scale level of thefirst frame as “1”, the gray scale levels of brightness (excluding “0”)of the second frame signal are the values obtained by adding ⅓ to eachof the gray scale levels of brightness (excluding “0”) of the firstframe, and the gray scale levels of brightness (excluding “0”) of thethird frame signal are the values obtained by adding ⅓ to each of thegray scale levels of brightness (excluding “0”) of the second frame. Inthis case, since the next higher gray scale value after “0” of the videosignal of the first frame is “1”, the next higher gray scale value after“0” of the video signal of the second frame is “1+⅓”, and the nexthigher gray scale value after “0” of the video signal of the third frameis “1+⅓+⅓”. Likewise, since the next higher gray scale value after “1”of the video signal of the first frame is “2”, the next higher grayscale value after “1+⅓” of the video signal of the second frame is“2+⅓”, and the next higher gray scale value after “1+⅓+⅓” of the videosignal of the third frame is “2+⅓+⅓”.

By applying the calculations described above three continuous frames ofoutput video signals are generated such that the gray scale level ofbrightness of a video image perceived by an observer viewing andintegrating three continuous video images (generated by the SLM 1002modulating the illumination light 1008 in accordance with of the threeframes of the output video signal) is approximately equal to theperceived gray scale level of brightness generated in accordance withthe frame signal of the input video signal.

With this operation, the expressible number of gray scales, inaccordance with the output video signals having the three continuousframes, is “256” (=8 bits). The number of gray scales of a video image,perceived by the observer viewing and integrating the video images ofthe three continuous frames, is approximately “768”, which is close to“1024” (=10 bits), the expressible number of gray scales s projected inaccordance with the input video signal. Therefore, the gray scale of avideo image perceived by the observer, when output video images areprojected in accordance with the output video signals, is close to thegray scale of the input video signal.

FIG. 21 is a diagram showing yet another exemplary operation of theimage processing unit 1017, SLM controller 1018, and spatial lightmodulator (SLM) 1002.

FIG. 21 exemplifies the case of generating, from an input video signalwhich has a 60 Hz frame rate and in which the video signal of each frameis capable of expressing gray scales of 1024 for each pixel, an outputvideo signal which has a 120 Hz frame rate and in which the video signalof each frame is capable of expressing gray scales of 341 for eachpixel.

In the present example, an output video signal generated within theperiod of one frame of an input video signal consists of signals ofthree frames, i.e., the video signal of the first frame, which isgenerated by converting the expressible number of gray scales from 1024into 341 for each pixel of the first frame of an input video image, andthe video signals of the second and third frames, which are generatedfrom the video signals of the first frame and second frame of the inputvideo signal by means of a motion image interpolation and which have anexpressible gray scale data of 341 for each pixel.

However, as with the exemplary operation described with reference toFIG. 20, for the three frames of output video signals, a pre-establishedrule determines the level of brightness of display video images on thebasis of the value of gray scale data (excluding “0”), which differamong the three frames of video signals. Also, according to thisexample, the rule is pre-established so that one-third (⅓) of the amountof change of brightness for each gray scale level expressible with thevideo signal of the first frame is designated as an offset amount. Thevalues obtained by adding the offset amount to each of the gray scalelevels of brightness (excluding “0”) expressible with the video signalof the first frame is designated as the gray scale levels of brightness(excluding “0”) expressible with the second frame signal. Similarly, thevalues obtained by adding the offset amount to each of the gray scalelevels of brightness (excluding “0”) expressible with the video signalof the second frame is designated as the gray scale levels of brightness(excluding “0”) expressible with the third frame signal.

By applying the calculations described above three continuous frames ofoutput video signals are generated such that the gray scale level ofbrightness of a video image perceived by an observer viewing andintegrating three continuous video images (generated by the SLM 1002modulating the illumination light 1008 in accordance with of the threeframes of the output video signal) is approximately equal to theperceived gray scale level of brightness generated in accordance withthe frame signal of the input video signal.

With this operation, the expressible number of gray scales of the threecontinuous video images projected in accordance with the three frames ofoutput video signals is “341”, whereas the expressible number of grayscales perceived by the observer viewing and integrating the videoimages of the three continuously outputted frames is approximately“1024”, which is the expressible number of gray scales of the videoimage projected in accordance with the input video signal. Therefore,the perceived gray scale of output video images, projected in accordancewith the output video signals having a plurality of continuous frames,is approximately equal to the gray scale of the video image of the inputvideo signal.

FIG. 22 is a diagram showing an exemplary operation when a color videoimage is displayed using the image processing unit 1017, SLM controller1018, and spatial light modulator (SLM) 1002.

FIG. 22 exemplifies the case of generating, from an input video signalwhich has a 60 Hz frame rate and in which each frame signal has 10-bitgray scale data for each of the colors R, G and B for each pixel, anoutput video signal which has a 120 Hz frame rate and in which eachframe signal has 9-bit gray scale data for each of the colors R, G and Bfor each pixel.

In this example, an output video signal generated within the period ofone frame of an input video signal consists of signals of three frames,i.e., the video signal of the first frame, generated by converting thegray scale data, 10-bit data into 9-bit data, of the first frame of aninput video signal for each color and each pixel, and the video signalsof the second frame and third frame, generated from the video signals ofthe first frame and second frame of the input video signal by means of amotion image interpolation and which has 9-bit gray scale data for eachcolor and each pixel.

More specifically, the video signal of each frame of the output videosignal has 9-bit gray scale data for each of the colors R, G and B andfor each pixel. Therefore the frame signal of the output video signalhas the video signal of an R sub-frame with R color data, a G sub-framewith G color data, and a B sub-frame with B color data.

For the three frames of output video signals, a pre-established ruledetermines the level of brightness of display video images on the basisof the value of gray scale data (excluding “0”), which differ among thethree frames of video signals. Additionally, the level of brightnessdetermined on the basis of the same value of gray scale data for eachcolor on the video signal of the same frame is pre-set to be the sameAlso, according to this example, the rule is pre-established so thatone-third (⅓) of the amount of change of brightness for each gray scalelevel expressible with the video signal of the first frame is designatedas an offset amount. The values obtained by adding the offset amount toeach of the gray scale levels of brightness (excluding “0”) expressiblewith the video signal of the first frame is designated as the gray scalelevels of brightness (excluding “0”) expressible with the second framesignal. Similarly, the values obtained by adding the offset amount toeach of the gray scale levels of brightness (excluding “0”) expressiblewith the video signal of the second frame is designated as the grayscale levels of brightness (excluding “0”) expressible with the thirdframe signal.

By applying the calculations described above three continuous frames ofoutput video signals are generated such that the gray scale level ofbrightness of a video image perceived by an observer viewing andintegrating three continuous video images (generated by the SLM 1002modulating the illumination light 1008 in accordance with of the threeframes of the output video signal) is approximately equal to theperceived gray scale level of brightness generated in accordance withthe frame signal of the input video signal.

With this operation, the expressible number of gray scales for one colorwhich is projected in accordance with the three frames of output videosignals is “512” (=9 bits), whereas the number of gray scales, perceivedby the observer viewing and sequentially integrating the video images ofthe three continuous output frames, is approximately “1536”. This numberexceeds “1024” (=10 bits), which is the expressible number of grayscales for each color projected in accordance with the input videosignal. Therefore, the gray scale of the video image perceived by theobserver when continuous video images are projected in accordance withcontinuous frames of the output video signal exceeds the gray scale ofthe video image of the input video signal.

FIG. 23 is a diagram showing yet another exemplary operation when acolor video image is displayed using the image processing unit 1017, SLMcontroller 1018 and spatial light modulator (SLM) 1002.

FIG. 23 exemplifies the case of generating an output video signal whichhas a higher frame rate than the input video signal, which has a 60 Hzframe rate, and in which each frame signal has 10-bit gray scale datafor each of the colors R, G and B for each pixel.

In the present example, an output video signal generated within theperiod of one frame of an input video signal consists of signals ofthree frames, i.e., the video signal of the first frame, which isgenerated by converting the gray scale data, 10-bit data into 9-bitdata, of the video signal of the first frame of the input video signalfor each color and each pixel, and the video signals of the second andthird frames, which are generated from the video signals of the firstand second frames of the input video signal by means of a motion imageinterpolation. The video signal of the second frame of the output signalhas 9-bit gray scale data for each color and each pixel, and the videosignal of the third frame of the output video signal has 2-bit grayscale data for each pixel.

Note that since the first and second frames of the output video signalshas 9-bit gray scale data for each of the colors R, G and B and for eachpixel, the frame signal of each of the video signal has the video signalof an R sub-frame with R color data, a G sub-frame with G color data,and a B sub-frame with B color data. Meanwhile, since the video signalof the third frame has 2-bit gray scale data for each pixel, it is alsothe frame with the black, white, or gray color data for each pixel. Thepresent example is configured to equip the third frame in order to add apseudo-gray scale and brightness.

In this case, however, the brightness of the three frames of outputvideo signals is determined in accordance with the value of gray scaledata (excluding “0”) and is designated differently for the video signalof the first frame than for the second frame. In this example, it ispredetermined that one-half (“½”) of the amount of change of brightnessper expressible gray scale level of the first frame is designated as anoffset amount, and that the values obtained by adding the offset amountto each of the expressible gray scale levels (excluding “0”) of thefirst frame is designated as the gray scale levels (excluding “0”) ofbrightness expressible with the video signal of the second frame.

By applying the rule described above, the two continuous frame signalsof the output video signals are generated so that the gray scale ofbrightness of a video image perceived by the observer viewing andintegrating the continuous video images (projected by the SLM 1002modulating the illumination light 1008 in accordance with the twocontinuous video signals of the output video signal) is approximatelyequal to the perceived gray scale of brightness of a video imageprojected by the SLM 1002 modulating the illumination light 1008 inaccordance with the input video signal.

With this operation, the expressible number of gray scales of each ofthe two continuous video images, projected in accordance with the outputvideo signals of the two continuous frames, is “512” (=9 bits), whereasthe number of gray scales, perceived by the observer viewing andsequentially integrating the two continuous video images, is “1024”.Thus the perceived number of gray scales, i.e., “1024” (=10 bits), isequal to the expressible number of gray scales for each color projectedin accordance with the input video signal. Therefore, the perceived grayscale of a video image, when a plurality of continuous video images isprojected onto a screen 1012 in accordance with the output video signalshaving a plurality of continuous frames, is approximately equal to thegray scale of the video image of the input video signal.

As described above, the present embodiment is configured to generate thevideo signals of a plurality of frames with different gray scalerepresentation and also to set the expressible number of gray scales ofeach of the video signals of the plurality of frames to be smaller thanthat of the frame signal of an input video signal, when an output videosignal with a higher frame rate than that of the input video signal isgenerated from the continuously inputted video signal. Thereby, it ispossible to process the video signals of the plurality of frames of theoutput video signal, constituting the video image of one frame of theinput video signal, within the period of one frame. It is furtherconfigured to perform a high speed display of a plurality of continuousframe output video images in accordance with the video signals of aplurality of continuous frames of an output video signal, and thereforea video image can be perceived by an observer as a smooth video image,maintaining the gray scale representation of the input video signal.

Third Preferred Embodiment

The following is a description of an exemplary operation of the imageprocessing unit 1017 included in the display processing unit 1006 as anexemplary operation according to the present embodiment of the videodisplay system 1001.

The present embodiment is configured to generate, from a continuouslyinputted video signal, an output video signal having a higher frame ratethan that of the input video signal. The input video signal has colorvideo image information, and each frame of the input video signal hasvideo data for each color of the color video image. In this case, theoutput video signal is configured so as to transmit the video signals ofthe sub-frames of the individual colors in sequence, and the outputvideo signal is configured so that the number of gray scales ofbrightness of each pixel of the video image of the sub-frame of eachcolor is smaller, or smaller in a portion of the output video signal,than the number of gray scales of the video data of each color in theinput video signal.

Then the sub-frame video images of the individual colors are formed bythe SLM controller 1018 and spatial light modulator (SLM) 1002 on thebasis of the output video signal and are sequentially displayed on thescreen 1012.

Although such an operation sets the number of gray scales of thesub-frame of each color in the output video signal to be smaller, orsmaller in a portion of the output video signal, than the number of grayscales of the video signal of each color in the input video signal, theframe rate of the output video signal is higher than that of the inputvideo signal. Therefore, a smoother motion image representation can beattained and the color breakup phenomena can be reduced while reducingthe load of the video signal processing and display processing performedin the later-stage circuit(s). Furthermore, a color video image withlittle degradation in the gray scale of a display video image can beprojected.

FIG. 24 is a diagram showing an exemplary operation of such an imageprocessing unit 1017.

Referring to FIG. 24, “input video signal” represents a video signalinput into the frame interpolation unit 1033, and “output video signal”represents a video signal output from the signal conversion unit 1034(this is the same for FIGS. 25 through 35, which are described later).Assuming that a video signal 1020 continuously inputted into the imageprocessing unit 1017 is a digital signal and that the resolution of theinput signal is the same as that of the video display system 1001, the“input video signal” constitutes a video signal 1020. Further, in FIG.24, the video image of the “input video signal” is an image of a ballmoving from the bottom left to the top right (this is the same for FIGS.25 through 35).

FIG. 24 exemplifies the case of generating an output video signal havinga 360 Hz frame rate from an input video signal having a 60 Hz framerate.

In the present example, an output video signal generated within theperiod of one frame of an input video signal consists of signals of sixframes, i.e., the video signal of the first frame which is generated byconverting the video signal of the first frame of the input videosignal, and the video signals of the second through sixth frames of theoutput video signal, which are generated from the video signals of thefirst frame and second frame of the input video signal by means of amotion image interpolation.

Here, the input video signal has gray scale data for each of the colorsR, G and B and for each pixel of each frame. The generated output videosignal has gray scale data for each of the colors R, G and B and foreach pixel of each frame and allows for a sequential display of thesub-frame images of the respective colors R, G and B. The output videosignal, however, is generated in a manner such that the number of grayscales of the sub-frame image for each of the colors R, G and B issmaller than the number of gray scales of the video data of each of thecolors included in the input video signal.

As an example, if number of gray scales of the video data of each of thecolors R, G and B in the input video signal is 1024 (=10 bits), thenumbers of gray scales sequentially displayable with the generatedoutput video signal are 128 (=7 bits) for the sub-frame image of thecolor R, 256 (=8 bits) for that of the color G, and 128 (=7 bits) forthat of the color B, as shown in FIG. 25. More specifically, the presentexample is configured to designate the number of gray scales (=256) forthe sub-frame image of G to be larger than the numbers of gray scales(=128) for those of R and B because the human eye is most sensitive togreen (G), and thereby the number of gray scales in the entire videoimage perceived by the human eye is increased.

Here, the total of the number of gray scales (the gray scale data) ofthe video images of each color included in the period of one frame ofthe input video signal is 3072, as represented by the followingexpression (1):[Number of gray scales of R]+[number of gray scales of G]+[number ofgray scales of B]=1024+1024+1024=3072  Expression (1)

Further, the total number of the gray scales (the gray scale data)included in six frames of the output video signals generated in theperiod of one frame of the input video signal is also 3072, as given bythe following expression (2):{[Number of gray scales of R sub-frame]+[number of gray scales of Gsub-frame]+[number of gray scales of Bsub-frame]}*6=(128+256+128)*6=3072  Expression (2)

With this operation, even though the numbers of gray scales of thesub-frame images for the colors R, G and B in the output video signal(that is, 128, 256, and 128) are smaller than the numbers of gray scalesof the sub-frame images for the colors R, G and B in the input videosignal (that is, 1024, 1024, and 1024), the frame rate of the outputvideo signal is six times that of the input video signal, making itpossible to project a smoother display of a motion image and toalleviate the color breakup phenomena, without a need to increase theload of the video signal processing and display processing performed ina later-stage circuit(s), and enabling the projection of a color videoimage with little degradation in gray scale of the video image as awhole.

More specifically, the example shown in FIG. 25 is enabled tosequentially display the sub-frame images of each color R, G and B perperiod of one frame of the output video signal in the same time width,and therefore the sub-frame image of each color has a 1080 Hz sub-framerate.

FIG. 26 is a diagram showing another exemplary operation of the imageprocessing unit 1017.

FIG. 26 exemplifies the case of generating an output video signal havinga 180 Hz frame rate from an input video signal having a 60 Hz framerate.

In this example, an output video signal generated within the period ofone frame of an input video signal consists of signals of three frames,i.e., the video signal of the first frame, which is generated byconverting the video signal of the first frame of the input videosignal, and the video signals of the second frame and third frame of theoutput video signal, which are generated from the video signals of thefirst frame and second frame of the input video signal by means of amotion image interpolation.

Here, the input video signal has 10-bit gray scale data for each of thecolors R, G and B for each pixel of each frame. Each of the generatedoutput video signals is a frame signal having 8-bit gray scale data ofR, 9-bit gray scale data of G, and 8-bit gray scale data of B, for eachpixel of each frame. Also since the human eye is most sensitive to thecolor green, the number of gray scales of the sub-frame image of thecolor G, that is, 512 (=9 bits) is larger than the numbers of grayscales of the sub-frame images of the other colors, R and B, both 256(=8 bits). As such, the output video signals are generated in a mannersuch that the numbers of gray scales of the sub-frame image of each ofthe colors R, G and B, respectively 256, 512 and 256, which aresequentially expressible with the generated output video signal, aresmaller than the number of gray scales in the video data of the colorsR, G and B, that is, 1024 (=10 bits), in the input video signal.

Here, the total number of the gray scales in the video images of thecolors included in the period of one frame of the input video image is3072, which is the value obtained by the above described expression (1).

Further, the total number of gray scales included in three frames of theoutput video signals generated in the period of one frame of the inputvideo signal is also 3072, as given by the following expression (3):{[Number of gray scales of R sub-frame]+[number of gray scales of Gsub-frame]+[number of gray scales of Bsub-frame]}*3=(256+512+256)*3=3072  Expression (3)

With this operation, even though the numbers of gray scales (256, 512,256) of the sub-frame images of the respective colors R, G and B in theoutput video signal are smaller than the numbers of gray scales (1024,1024, 1024) of the respective colors R, G and B in the input videosignal, the frame rate of the output video signal is three times that ofthe input video signal, making it possible to project a smoother displayof a motion image and to alleviate the color breakup phenomena withoutincreasing the load of the video signal processing and displayprocessing performed in a later-stage circuit(s), enabling theprojection of a color video image with little degradation in the grayscale of the video image as a whole.

Note that, in the example shown in FIG. 26, the sub-frame images of thecolors R, G and B for the period of one frame of the output videosignals can be sequentially displayed in the same time width, andtherefore the sub-frame image of each color has a 540 Hz sub-frame rate.

FIG. 27 is a diagram showing yet another exemplary operation of theimage processing unit 1017.

FIG. 27 exemplifies the case of generating an output video signal havinga 360 Hz frame rate from an input video signal having a 60 Hz framerate.

In this example, an output video signal generated within the period ofone frame of an input video signal consists of signals of six frames,i.e., the video signal of the first frame, which is generated byconverting the video signal of the first frame of the input videosignal, the video signals of the second, fourth and fifth frames,generated from the video signals of the first and second frames of theinput video signals by means of a motion image interpolation, and thevideo signals of the third frame and sixth frame which is generated onthe basis of the video signals of the first frame and second frame ofthe input video signal.

Here, the input video signal has 10-bit gray scale data for each of thecolors R, G and B and for each pixel of each frame.

Further, the first frame and fourth frame of the output video signalshave gray scale data for each of the colors R, G and B and for eachpixel, while the second frame and fifth frame have gray scale data foreach of the colors Cyan (C), magenta (M) and yellow (Y). The third frameand sixth frame have gray scale data for setting all pixels to be anachromatic color, such as white (W), gray (Gy) or black (K) and is alsoa frame capable of displaying all pixels in an achromatic color.

More specifically, the output video signal is generated in a manner suchthat the number of gray scales of the sub-frame of each of the colors R,G and B, sequentially expressible with the first and forth frame; thenumber of gray scales of the sub-frame of each of the colors C, M and Y,sequentially expressible with the second and fifth frame; and the numberof gray scales of the sub-frame of one of the colors W, Gy and K,expressible with the third and sixth frame, are respectively smallerthan the number of gray scales in the video data of each of the colorsR, G and B in the input video signal.

With this operation, even though the number of gray scales of thesub-frame of each of the colors and the number of gray scales of theframe image expressible with the output video signal are smaller thanthe number of gray scales in the video data of each of the colors R, Gand B in the frame signal of the input video signal, the frame rate ofthe output video signal is six times that of the input video signal.This makes it possible to project a smoother display of a motion imageand to alleviate the color breakup phenomena without increasing the loadof the video signal processing and display processing performed in alater-stage circuit(s), enabling the projection of a color video imagewith little degradation in the gray scale of the video image as a whole.

Incidentally, the illumination light 1008 of the respective colors C, M,Y, W and Gy can be projected by controlling at least two of the threelaser light sources R, G and B of the variable light sources 1013 toemit light simultaneously.

FIG. 28 is a diagram showing yet another exemplary operation of theimage processing unit 1017.

FIG. 28 exemplifies the case of generating an output video signal havinga 240 Hz frame rate from an input video signal having a 60 Hz framerate.

In this example, an output video signal generated within the period ofone frame of an input video signal consists of signals of four frames,i.e., the video signal of the first frame, generated by converting thevideo signal of the first frame of the input video signal, and the videosignals of the second, third, and fourth frames, which are generatedfrom the video signals of the first frame and second frame of the inputvideo signals by means of a motion image interpolation.

Here, the input video signal has 10-bit gray scale data for each of thecolors R, G and B and for each pixel of each frame.

Further, the generated output video signals are video signals havinggray scale data for each of the colors R, G and B for each pixel of eachframe and are also sequentially displayable frame signals with thesub-frame images of the colors R, G and B in different time widths.Further, the generated output video signals are frame signals enabled todisplay the sub-frame image of R one time, the sub-frame image of G twotimes, and the sub-frame image of B one time in each period of one frameof the output video signal.

However, the output video image is generated in a manner such that thenumber of gray scales of the sub-frame image of each of the colors R, Gand B, are smaller than the number of gray scales in the video data ofeach of the colors R, G and B in the input video signal, 1024 (=10bits).

With this operation, even though the number of gray scales of thesub-frame image of each of the colors in the output video signal issmaller than the number of gray scales in the video data of each of thecolors R, G and B in the input video signal, the frame rate of theoutput video signal is four times that of the input video signal. Thismakes it possible to project a smoother display of a motion image and toalleviate the color breakup phenomena without increasing the load of thevideo signal processing and display processing performed in alater-stage circuit(s), enabling the projection of a color video imagewith little degradation in the gray scale of the video image as a whole.

Further, this configuration makes it possible to set the number of timesthe sub-frame image of G, to which the human eye has the highestsensitivity, is displayed to be greater than the number of times thesub-frames of other colors, for each period of one frame of the outputvideo signal, are displayed, thereby enabling a further reduction in theoccurrence of the color breakup phenomena.

FIG. 29 is a diagram showing yet another exemplary operation of theimage processing unit 1017.

FIG. 29 exemplifies the case of generating an output video signal havinga 180 Hz frame rate from an input video signal having a 60 Hz framerate.

In this example, an output video signal generated within the period ofone frame of an input video signal consists of signals of three frames,i.e., the video signal of the first frame generated by converting thevideo signal of the first frame of the input video signal, the videosignal of second frame generated from the video signals of the first andsecond frames of the input video signals by means of a motion imageinterpolation, and the video signal of the third frame generated on thebasis of the video signals of the first and second frames of the inputvideo signal.

Here, the input video signal is a frame signal having 10-bit gray scaledata for each of the colors R, G and B and for each pixel.

Further, the first and second frames of the generated output videosignals have 9-bit gray scale data of R, 10-bit gray scale data of G,and 8-bit gray scale data of B for each pixel. They are also framesignals enabled to sequentially display the sub-frame images of thecolors R, G and B for different lengths of time, and are further enabledto extend the display time of the sub-frame image of G to be longer thanthe display time of the sub-frames of R and B within the period of oneframe of the output video signal. The display time of the sub-frameimage of B may also be controlled to be shorter than the display time ofthe sub-frames of R and G within the period of one frame of the outputvideo signal. The third frame signal is a frame having gray scale datafor setting all pixels to be an achromatic color such as white (W), gray(Gy) or black (K) and is also capable of displaying all pixels in anachromatic color.

As described above, in the sub-frame images of the colors R, G and B,the first and second frames of the output video image are generated in amanner such that the numbers of gray scales (512 and 256, respectively)of the sub-frame image of the respective colors R and B are smaller thanthe number of gray scales (1024) in the video data of each of the colorsR and B in the input video signal. Further, the number of gray scales(1024) of the sub-frame image of G is equal to the number of gray scales(1024) of the sub-frame image of G in the input video signal. Meanwhile,for the third frame signal, the output video signal is generated in amanner such that the number of gray scales in an achromatic frame imageis smaller than the number of gray scales (1024) in any of the videodata of the colors R, G and B in the input video signal.

With this operation, even though the numbers of gray scales (512, 1024and 256) of the sub-frame images of the respective colors R, G and B,sequentially displayable with the output video signal, are smaller forsome colors than the number of gray scales (1024) in the video data inthe input video signal, the frame rate of the output video signal isthree times that of the input video signal, making it possible toproject a smoother display of a motion image and to alleviate the colorbreakup phenomena without increasing the load of the video signalprocessing and display processing performed in a later-stage circuit(s),thus enabling the projection of a color video image with littledegradation in the gray scale of the video image as a whole.

In particular, the present example is configured to decrease, by agreater number than that for the sub-frame image of R, the number ofgray scales of the sub-frame image of B, to which the human eye has lowsensitivity, without decreasing the number of gray scales of thesub-frame image of Q to which the human eye has high sensitivity, andalso to set the length of display time of the sub-frame image of G to bethe longest while setting the length of display time of the sub-frameimage of B to be the shortest. Therefore it is possible to achieve theprojection benefits described above.

FIG. 30 is a diagram showing an exemplary modification of the exemplaryoperation shown in FIG. 29.

In the example shown in FIG. 30, the first and second frames of thegenerated output video signal have 10-bit gray scale data of R, 10-bitgray scale data of G, and 8-bit gray scale data of B for each pixel. Itis possible to set the length of display time of the sub-frame image ofB to be shorter than the display time of the other colors and also toset the display time of the sub-frame image of R and that of thesub-frame image of G to be approximately the same. Incidentally, thethird frame is controlled in the same manner as the example shown inFIG. 29.

As described above, in the sub-frame images of the colors R, G and B,which can be sequentially displayed with the output video signal, thefirst and second frames of the output video image are generated in amanner such that the number of gray scales (1024) of the sub-frame imageof each of the colors R and G is equal to the number of gray scales(1024) of the sub-frame image of each of the colors R and G in the inputvideo signal, and the number of gray scales (256) of the sub-frame imageof B is smaller than the number of gray scales (1024) of the sub-frameimage of B in the input video signal.

Such an operation also makes it possible to project a smoother displayof a motion image and to reduce the occurrence of the color breakupphenomena, while suppressing an extreme increase in the load of thevideo signal processing and display processing, enabling the projectionof a color video image with little degradation in the gray scale of thevideo image as a whole, as with the example shown in FIG. 29.

In particular, the present example is configured to decrease only thenumber of gray scales of the sub-frame image of B, to which the humaneye has low sensitivity, without decreasing the numbers of gray scalesof the sub-frame images of G, to which the human eye has highsensitivity, and also to set the length of display time of the sub-frameimage of B to be the shortest.

FIG. 31 is a diagram showing yet another exemplary operation of theimage processing unit 1017.

FIG. 31 exemplifies the case of generating an output video signal havinga 240 Hz frame rate from an input video signal having a 60 Hz framerate.

In this example, an output video signal generated within the period ofone frame of an input video signal consists of signals of four frames,the video signal of the first frame generated by converting the videosignal of the first frame of the input video signal, and the videosignals of the second, third, and fourth frames generated from the videosignals of the first frame and second frame of the input video signalsby means of a motion image interpolation.

Here, the input video signal has 10-bit gray scale data for each of thecolors R, G and B and for each pixel of each frame.

Further, the first and third frames of the output video signal have8-bit gray scale data of R, 5-bit gray scale data of M, 8-bit gray scaledata of G, 5-bit gray scale data of Y, 7-bit gray scale data of B, and5-bit gray scale data of C, for each pixel. Further, each of the twoframes has video signals sequentially displayable with the sub-frameimages of the colors R, M, G, Y, B and C. Specifically, each of the twoframes is enabled to insert, between the sub-frame images of twoadjacent primary colors R, G or B, the sub-frame image of onecomplementary color M, Y or C. In particular, this example is configuredto enable the display of the sub-frame image of a complementary color(e.g., M) containing a primary color (e.g., R) next to the sub-frameimage of the primary color and to display, following the sub-frame imageof the aforementioned complementary color, the display of the sub-frameimage of a primary color (e.g., G), which is not contained in thecomplementary color.

Furthermore, each of the two frames can be configured such that thelength of display time of the sub-frame image of each of the colors R, Gand B is longer than that of the colors M, Y and C. The length ofdisplay time of the sub-frame images of the colors R and G are the sameas each other and shorter than that of displaying the sub-frame of B.The length of display time of the sub-frames of M, Y and C are the same.

Further, the second frame and forth frame of the generated output videosignal have 8-bit gray scale data of R, 9-bit gray scale data of G, and8-bit gray scale data of B for each pixel. Each of the two frames hasvideo signals sequentially displayable with the sub-frame images of thecolors R, G and B. Furthermore, each of the two frames is also a framesignal which is enabled to set the length of display time of thesub-frame image of G to be longer than each of the sub-frames of R andB, and also to set the length of display time of the sub-frame images ofR and B to be the same.

As such, a frame signal is generated such that the numbers of grayscales (256, 32, 256, 32, 128, and 32) of the sub-frame images of eachof the respective colors R, M, G, Y, B and C, which are sequentiallydisplayable with each of two frame signals (the first and third frame),and the numbers of gray scales (256, 512, and 256) of the sub-frameimages of each of the respective colors R, G and B, which aresequentially displayable with each of two frame signals (the second andforth frame), are smaller than the number of gray scales (1024) of thesub-frame image of each of the colors R, G and B, which are sequentiallydisplayable with the frame signals of the input video signal.

With this operation, even though the numbers of gray scales (256, 32,256, 32, 128 and 32) of the sub-frame image of each of the respectivecolors R, M, G, Y, B and C and the numbers of gray scales (256, 512, and256) of the sub-frame image of each of the respective colors R, G and B,all of which are sequentially displayable with the output video signal,are smaller than the number of gray scales (1024) in the video data ofeach of the colors R, G and B in the input video signal, the frame rateof the output video signal is four times that of the input video signal.This makes it possible to project a smoother display of a motion imageand to alleviate the occurrence of the color breakup phenomena withoutincreasing the load of the video signal processing and displayprocessing, thus enabling the projection of a color video image withlittle degradation in the gray scale of the whole video image.

In particular, in this example, in the first and third frames of theoutput video signals it is possible to display, next to the sub-frameimage of a primary color, the sub-frame image of a complementary colorcontaining the aforementioned primary color and, in the next sub-frame,a primary color which is not contained in the aforementionedcomplementary color, thereby enabling a further reduction in theoccurrence of the color breakup phenomena.

Further, this example designates the length of display time of thesub-frame image of G, to which the human eye has a high sensitivity, tobe longer than that of other colors and also designates the number ofgray scales of the color G to be larger than those of other colors,making it possible to provide a video image with less degradation in thegray scale.

FIG. 32 is a diagram showing an exemplary modification of the exemplaryoperation shown in FIG. 31.

In FIG. 32, the second and fourth frames, among four frames of theoutput video signal generated within the period of one frame of theinput video signal, are frame signals further having 2-bit gray scaledata of W for each pixel. That is, each of the two frame signals is aframe signal having 8-bit gray scale data of R, 9-bit gray scale data ofG, 8-bit gray scale data of B, and 2-bit gray scale data of W for eachpixel. Further, each of the two frames has a video signal capable ofsequentially displaying the sub-frame images of the colors R, G, B andW. Each of the two frames is enabled to set the length of display timeof the sub-frame image of G to be the longest, to set that of thesub-frame image of W to be the shortest, and to set the that of thesub-frames of R and B to be equal to each other, with the length ofdisplay time for R and B being shorter than G and longer W.Incidentally, the first and third frames are controlled in the samemanner as the example shown in FIG. 31.

As such, the output video signal is generated so that the numbers ofgray scales (256, 512, 256, and 4) in the sub-frame images of therespective colors R, G, B and W, sequentially displayable with in thesecond and fourth frames, is smaller than the number of gray scales(1024) of the video data of each of the colors R, G and B in the inputvideo signal.

Also, similar to the example shown in FIG. 31, such an operation makesit possible to alleviate the color breakup phenomena without increasingthe load of the video signal processing and display processing performedin a later-stage circuit(s) and to project a color video image withlittle degradation in the gray scale of the video image as a whole.

In particular, the present example enables the second and fourth frames,from among four frames of the output video signal generated within theperiod of one frame of the input video signal, to further display thesub-frame of W, thereby making it possible to project a brighter colorvideo image.

More specifically, the present example is configured such the second andfourth frames include 2-bit gray scale data of W. Alternately, theaforementioned frames may contain 1-bit or 3-bit gray scale data of W,in accordance with the processing capability of the image processingunit 1017.

When an output video signal is generated and outputted, as described inthe exemplary operations of the image processing unit 1017, withreference to FIGS. 24 through 32, then the sub-frame images of thecolors, in accordance with the output video signal, are sequentiallyprojected onto the screen 1012 with the processing of the later-stagecircuit(s). The variable light source 1013 emits laser lights ofdifferent colors in synch with the sub-frame images of the colors to beprojected onto the screen 1012.

FIG. 33 is a diagram showing an exemplary emission of the variable lightsource 1013.

The exemplary emission shown in FIG. 33 shows the laser lights ofdifferent colors synchronously emitting light with the sub-frame imagesof the respective colors to be projected onto the screen 1012, inaccordance with the output video signal generated by the exemplaryoperation described with reference to FIG. 26.

The present example is a case of sequentially displaying the sub-frameimages of the colors R, G and B using color laser light sources and SLM1002. Specifically, the red laser light is irradiated during the periodfor displaying the R sub-frame image, the green laser light isirradiated during the period for displaying the G sub-frame image, andthe blue laser light is irradiated during the period for displaying theB sub-frame image so that the lights from the respective color lightsources are sequentially irradiated onto the SLM 1002 so as to form thesub-frame images corresponding to the lights of the respective colorsand are projected onto the screen 1012 and displayed.

FIG. 34 shows an exemplary modification of the exemplary emission shownin FIG. 33.

In this example, the red, green and blue laser light sourcessequentially emit laser lights during the projection period of therespective sub-frame images of R, G and B, and the emission patterns ofthe respective laser light sources of red, green and blue are changed inaccordance with the projection period of the respective sub-frameimages.

In the period for projecting the R sub-frame image, there are twoperiods (T_(R)) for emitting the red laser light source, two periods(T_(G)) for emitting the green laser light source, and two periods(T_(B)) for emitting the blue laser light source, in the order of R, G,B, R, G and B. However, the period T_(G) and period T_(B) are each muchshorter than the period T_(R).

Likewise, in the period for projecting the G sub-frame image, there aretwo periods each for emitting the red laser light source, the greenlaser light source, and the blue laser light source, in the order of R,G, B, R, G and B. However, the periods emitting the red laser lightsource and the blue laser light source are each much shorter than theperiods emitting the green laser light source.

Further, in the period for projecting the B sub-frame image, there aretwo periods each for emitting the red laser light source, the greenlaser light source, and the blue laser light source, in the order of R,G, B, R, G and B. However, the periods emitting the red laser lightsource and the green laser light source are each much shorter than theperiods emitting the blue laser light source.

As described above, by causing the laser light sources of the othercolors to sequentially emit a minute amount of light during theprojection period for the sub-frame image of each of the colors R, G andB, it is possible to further reduce the occurrence of the color breakupphenomena. Further, by adjusting the ratio of periods emitting lights ofthe respective colors in the period of each sub-frame it is possible toadjust color balance.

FIG. 35 is a diagram showing another exemplary emission of the variablelight source 1013.

The exemplary emission shown in FIG. 35 is the case of controlling thelaser light sources of the individual colors to emit light synchronouslywith the sub-frame images of the respective colors to be projected ontothe screen 1012, in accordance with the output video signal generated,as the exemplary operation described with reference to FIG. 31.

In the example, the output video signals of the first and third frameshave a video signal enabling a sequential display of the sub-frameimages of the respective colors R, M, G, Y, B and C, while the signalsof the second and fourth frames have a video signal enabling asequential display of the sub-frame images of the respective colors R, Gand B. Therefore, for example, when the sub-frame images of R, M, G, Y,B and C are projected onto the screen 1012, in accordance with the firstframe and third frame, the red laser light source is irradiated duringthe period for projecting the R sub-frame image. Two laser lightsources, the red and blue light sources, are irradiated simultaneouslyduring the period for projecting the M sub-frame image. The green laserlight source is irradiated during the period for projecting the Gsub-frame image. Two laser light sources, the red and green laser lightsources, are irradiated simultaneously during the period for projectingthe Y sub-frame image. The blue laser light source is irradiated duringthe period for projecting the B sub-frame image. Two laser lightsources, the green and blue laser light sources, are irradiated duringthe period for projecting the C sub-frame image.

More specifically, the configuring as described above, in which thesub-frame images of the respective colors are projected onto the screen1012 in order of R, M, G, Y, B and C, controls the laser light sourcesto emit light two times during the period of one frame, making itpossible to shorten the emission cycle of the laser light source of eachcolor and further reduce the occurrence of the color breakup phenomena.

In the exemplary emissions shown in FIGS. 33 through 35, the emissioncycles of the laser light sources of the colors R, G and B are shorterthan the sub-frame rate cycles of the sub-frame images of the respectivecolors R, G and B, which are sequentially displayable with the framesignals of the input video signal.

As described above, the present embodiment is configured to generate anoutput video signal, such that the number of gray scales of thesub-frame image of each of the colors (or in a portion of the outputvideo signal) is smaller than the number of gray scales of the videodata of the sub-frame of each of the colors in an input video signal.The output video signal has a higher frame rate than that the inputvideo signal from which it is generated. This makes it possible toproject a smooth motion image and alleviate the color breakup phenomena,without increasing the load of the video signal processing and displayprocessing performed in a later-stage circuit(s), and to project a colorvideo image with little degradation in the gray scale of the image as awhole.

Fourth Preferred Embodiment

The following is a description of an exemplary operation according tothe present embodiment of a video display system 1001.

The video display system 1001, according to the present embodiment, is asystem generating an output video signal with a higher frame rate thanthat of an input video signal from a continuously inputted video signaland displaying a video image in accordance with the generated outputvideo signal, as in the case of the above described embodiment.

The present embodiment, however, is configured to generate, as an outputvideo signal for each period of one frame of an input video signal, thevideo signal of at least the first frame, having N-bit gray scale datafor each pixel (where N<M), and the video signal of a second frame,having N′-bit gray scale data for each pixel (where N′<N) at the imageprocessing unit 1017, and to output the generated video signals from thesignal conversion unit 1034, when a video signal having M-bit gray scaledata for each pixel (where N<M and N′<N) is continuously inputted intothe frame interpolation unit 1033 as the input video signal. Further,the configuration is such that, when a display unit displays a videoimage in accordance with the output video signal, the weight ofbrightness per unit of the first control, used when a video image isdisplayed in accordance with the video signal of the first frame, isdifferentiated from the weight of brightness per unit of second control,used when a video image is displayed in accordance with the video signalof the second frame. Here, the “display unit” is a generic term for thecomprisal including the light source optical system 1005 (which is alsoan illumination optical system), SLM 1002, SLM controller 1018, andlight source controller 1019.

FIG. 36 is a diagram showing an exemplary operation of such a videodisplay system 1001.

Referring to FIG. 36, more specifically, “input video signal” representsa video signal inputted into the frame interpolation unit 1033, and“output video signal” represents a video signal outputted from thesignal conversion unit 1034 (all of which are the same for FIGS. 37 and38, which are described later). Assuming that a video signal 1020continuously inputted into the image processing unit 1017 is a digitalsignal and also that the resolution of the video signal 1020 is the sameas that of the video display system 1001, the “input video signal”constitutes the video signal 1020. The video image of “input videosignal” is a video image of a ball moving from the bottom left to thetop right (which is the same for FIGS. 37 and 38).

FIG. 36 exemplifies the case of generating an output video signal with a120 Hz frame rate from an input video signal with a 60 Hz frame rate andin which each frame has 10-bit (i.e., an example of the M-bit describedabove) gray scale data for each pixel.

In this example, an output video signal generated within the period ofone frame of an input video signal consists of signals of two frames,1.) the video signal of the first frame generated by converting the grayscale data of the video signal of the first frame of an input videosignal for each pixel, that is, 10-bit data into 9-bit data (i.e., anexample of the N-bit described above), and 2.) the video signal of thesecond frame generated from the first and second frames of the inputvideo signal by means of a motion image interpolation and which has8-bit (i.e., an example of the N′-bit described above) gray scale datafor each pixel.

Then, when the display unit displays a video image in accordance withthe output video signal, the weight of brightness per unit of firstcontrol, used when a video image is displayed in accordance with thevideo signal of the frame having 9-bit gray scale data for each pixel,is differentiated from the weight of brightness per unit of secondcontrol, is used when a video image is displayed in accordance with thevideo signal of the frame having 8-bit gray scale data for each pixel.The present example is configured to carry out the processing bydesignating the weight of brightness per unit of second control to betwo times that of the first control.

More specifically, in this example, the unit of the first control is theminimum unit of control used when a video image is displayed inaccordance with the video signal of the frame having 9-bit gray scaledata for each pixel, corresponding to the LSB of 9 bits. Similarly, theunit of the second control is the minimum unit of control used when avideo image is displayed in accordance with the video signal of theframe having 8-bit gray scale data for each pixel, corresponding to theLSB of 8 bits.

With the control as described above, even though the number of grayscales (256) of the video image with 8-bit gray scale data for eachpixel is smaller than the number of gray scales (512) of the video imagewith 9-bit gray scale data for each pixel, the number of gray scales ina synthesized video image, produced by a combination of the two videoimages, is approximately the same as the number of gray scales (512) ofthe video image with 9-bit gray scale data for each pixel. Therefore,according to this example, the gray scale data volume of one of the twooutput video signals, generated within the period of one frame of aninput video signal, is smaller than the gray scale data volume of theother. Therefore, the load of the video signal processing and displayprocessing can be reduced. Furthermore, a video image display capable ofexpressing approximately the same number of gray scales, as that of avideo image displayed in accordance with the video signal of the framewith the larger number of gray scales, can be attained.

FIG. 55 is an example of displaying the first frame at 512 gray scales(9 bits) and the second frame at 341 gray scales (a number between 8bits and 9 bits), of two frames of the output video signals shown inFIG. 36. Here, the LSB period used in the video signal of the secondframe is 1.5 times that of the first frame. Further, the brightnessobtained by controlling the SLM 1002 under the ON state for the LSBperiod of the video signal of the second frame is 1.5 times thebrightness obtained by controlling the SLM 1002 under the ON state forthe LSB period of the video signal of the first frame.

In this event, one step of gray scale of brightness obtained in thesecond frame is 1.5 times that of the first frame. The levels ofbrightness for the time in two steps of the gray scale of brightness(e.g., 1.5, 4.5 and 7.5) is obtained in the second frame that have thelevels of brightness which are not presented in the gray scale ofbrightness (e.g., 1, 2, 3, 4, 5, 6 and 7) that is obtained in the firstframe. Specifically, by combining the first frame and second frame, withdiffering LSB periods, it is possible to display a video image usinggreater gray scale levels of brightness than when using only the firstframe.

FIG. 37 is a diagram showing a specific example of a method of settingthe weight of brightness per unit of second control at two times theweight of brightness per unit of first control, in the example shown inFIG. 36.

FIG. 37 exemplifies the case of setting the weight of brightness perunit of the second control at two times that of the first control bydesignating the period of time per unit of the second control to be twotimes that of the first control, when the light intensity of theillumination light 1008 irradiated in the period of time per unit of thefirst and second controls are set to be constant and equal to eachother.

According to this example, the first frame signal has 512 gray scales(i.e., 9-bit gray scale data) for each pixel, and therefore, the periodof time per LSB of 9 bits, corresponding to the unit of the firstcontrol, is 16.3 (=1/120/512) microseconds (μsec). Further, the secondframe signal has 256 gray scales (i.e., 8-bit gray scale data) for eachpixel, and therefore, the period of time per LSB of 8 bits,corresponding to the unit of the first control, is 32.6 (=1/120/256)μsec. Therefore, the period of time per unit of the second control (32.6μsec) is two times the period of time per unit of the first control(16.3 μsec). Meanwhile, the light intensity of the illumination light1008 irradiated in each frame period of the output video signal isconstant and equal, although this is not shown in the figure.

With this operation, it is possible to set the weight of brightness perunit of the second control at two times the weight of brightness perunit of the first control.

More specifically, in the example shown in FIG. 37, the input videosignal has 1024 gray scales (i.e., 10-bit gray scale data) for eachpixel of each frame. Therefore, the period of time per LSB of 10 bits,corresponding to the unit of control used when a video image isdisplayed in accordance with the input video signal, is 16.3(=1/60/1024) μsec, which equals the difference (16.3 μsec) between theperiod of time per unit of the first control and that of the secondcontrol. Therefore, the difference between the weight of brightness perunit of the first control and that of the second control is equivalentto one LSB of 10 bits, which corresponds to the unit of control of theinput video signal in this example.

FIG. 38 is a diagram showing another specific example of a method ofsetting the weight of brightness per unit of second control at twice theweight of brightness per unit of first control.

FIG. 38 exemplifies the case of setting the period of time per unit ofthe second control to be the same as that of the first control, and alsoof setting the light intensity of the illumination light 1008 irradiatedin the period of time per unit of the second control at two times thatof the first control, thereby designating the weight of brightness perunit of the second control to be two times that of the first control.

More specifically, the example shown in FIG. 38 is similar to theexamples shown in FIGS. 36 and 37, where the video signals of the twoframes of the output video signal have 9-bit gray scale data and 8-bitgray scale data. However, the present example differs from the examplesshown in FIGS. 36 and 37 in that the frame rate of the output videosignal is 120 Hz.

In this example, the video signal of the first frame has 512 gray scales(i.e., 9-bit gray scale data) for each pixel and the video signal of thesecond frame has 256 gray scales (i.e., 8-bit gray scale data) for eachpixel, with the period of time per unit of the first control equal tothe period of time per unit of the second control. Therefore the periodof time per each unit of the first control and second control isapproximately 21.7 (=1/60/(512+256) μsec. Further, the light intensityof the illumination light 1008 irradiated during the frame period of thevideo signal of the second frame is two times that of the first frame.

With this operation, it is possible to set the weight of brightness perunit of the second control at two times the weight of brightness perunit of the first control.

FIG. 56 is a diagram showing a specific example of a method which setsthe weight of brightness per unit of second control at 1.5 times theweight of brightness per unit of first control.

FIG. 56 exemplifies the case of setting the period of time per unit ofthe second control to be the same as the period of time per unit of thefirst control, and also of setting the light intensity of theillumination light 1008 irradiated in the period of time per unit of thesecond control at one and a half (1.5) times that per unit of the firstcontrol, thereby designating the weight of brightness per unit of thesecond control to be 1.5 times that of the first control.

More specifically, the example shown in FIG. 56 is the same as theexample shown in FIG. 55, in which the output video signal constitutesone frame having 512 (9-bit) gray scales and the other frame having 341gray scales for each pixel. The example in FIG. 56 differs from that ofFIG. 55 in that the frame rate of the output video signal is 120 Hz.

In FIG. 56, the first frame has 512 gray scales (i.e., 9-bit gray scaledata) for each pixel, and the video signal of the second frame has 341gray scales (i.e., between 9-bit gray scale data and 8-bit gray scaledata) for each pixel, with the period of time per unit of the firstcontrol equal to the period of time per unit of the second control. Theperiod of time per each unit of the first control and second control isapproximately 19.5 (=1/60/(512+341) μsec. Further, the light intensityof the illumination light 1008 irradiated during the second frame periodis 1.5 times that irradiated during the first frame period.

With this operation, it is possible to set the weight of brightness perunit of the second control at 1.5 times that of the first control.

As described above, the present embodiment is configured to generate, asthe frame of an output video signal for each period of one frame of aninput video signal, at least a first frame having N-bit gray scale datafor each pixel (where N<M), and a second frame having N′-bit gray scaledata for each pixel (where N′<N), when a frame having M-bit gray scaledata for each pixel (where N<M and N′<N) is continuously inputted as theinput video signal. Further, the configuration is such that, when avideo image is displayed in accordance with the output video signal, theweight of brightness per unit of the first control, used when a videoimage is displayed in accordance with the first frame, is differentiatedfrom that of the second control, used when a video image is displayed inaccordance with the second frame. With this operation, the total grayscale data volume of at least two frames of the output video signal,generated within the period of one frame of the input video signal, issmaller than the gray scale data volume generated within the period ofone frame of the input video signal. This makes it possible to reducethe load of the video processing and display processing. In addition, bycombining the video images displayed in accordance with theaforementioned two frames, it is possible to project a video imagedisplay capable of expressing approximately the same number as, or agreater number of gray scales than, that of a video image displayed inaccordance with the aforementioned frame with a larger number of grayscales. Therefore, it is possible to alleviate the load of the videoimage processing and display processing and to minimize degradation inthe gray scale of a video image, as perceived by the human eye, whiledecreasing the information volume of an output video signal with a highframe rate.

Fifth Preferred Embodiment

The following is a description of an exemplary operation according tothe present embodiment of a video display system 1001.

The video display system 1001 according to the present embodiment is asystem projecting a color video image by means of a color sequentialmethod, according to the third embodiment described above.

The present embodiment, however, is configured to provide a period fordisplaying the sub-frame image of each color of a plurality of primarycolors and a plurality of complementary colors within the period of oneframe of an output video signal, and to display the sub-frame images ofthe colors in sequence, thereby displaying a color video image. FIGS. 39through 43 are diagrams each showing an example of providing such aperiod. More specifically, the period of one frame shown in each figuremay be repeated in the all frame periods of an output video signal ormay be repeated in one or more frame periods. Further, the frame rate ofthe output video signal is, for example, 360 Hz.

FIG. 39 illustrates the process of providing a period for displaying thesub-frame of each of the primary colors R, G and B and of thecomplementary colors C, M and Y within the period of one frame of theoutput video signal so as to minimize the number of times each of threelaser light sources (i.e., red-, green- and blue laser light sources)emit light, and of displaying the sub-frame images of the respectivecolors in sequence, thereby displaying a color video image.

The present example is configured with the periods for displaying thesub-frame images of the three primary colors and the three complementarycolors in the order of R, Y, G, C, B and M, within the period of oneframe. As such, the present embodiment is configured display, at leastthe sub-frame image of a first primary color, the sub-frame image of afirst complementary color containing the first primary color, thesub-frame of a second primary color contained in the first complementarycolor, and the sub-frame image of a second complementary colorcontaining the second primary color, in the aforementioned order, suchas R, Y, G and C among the colors R, Y, G, C, B and M.

According to the present embodiment, since the sub-frame image of aprimary color contained in a complementary color is displayed before andafter the sub-frame image of the complementary color, it is possible tominimize the occurrence of the color breakup phenomena perceived by thehuman eye, when a color video image is displayed by sequentiallydisplaying the sub-frame images of the respective colors.

Further, by displaying the sub-frame images of the respective colors inthe order of R, Y, G, C, B and M within the period of one frame, it ispossible for each laser light source in the variable light source 1013to emit only once within the period of one frame. More specifically, inFIG. 39, the red laser light source (Red Laser) is emitted twice, andthe green laser light source (Green Laser) and the blue laser lightsource (Blue Laser) are emitted once within the period of one frame.However, if the period shown in FIG. 39 is repeated, the red laser lightsource emits an average of one time per period, and therefore the numberof times the red laser light source is emitted can be regarded as “1”.

FIGS. 40 and 41 exemplify the case of providing a period for displayingthe sub-frame image of each color of three primary colors R, G and B andof three complementary colors C, M and Y within the period of one frameof an output video signal so that the number of times each of threelaser light sources, included in the variable light source 1013, isemitted is maximized.

FIG. 40 exemplifies the case of displaying sub-frame images of therespective colors of the three primary colors and three complementarycolors in the order of R, C, G, M, B and Y within the period of oneframe. As such, the present embodiment is configured to continuouslydisplay, within the period of one frame, at least the sub-frame image ofa first primary color, the sub-frame image of a first complementarycolor composed in part of the first primary color, the sub-frame imageof a second primary color which does not compose the first complementarycolor, and the sub-frame image of the second complementary colorcomposed in part of the second primary color, in the aforementionedorder, such as the order of R, C, G and M from among the colors R, C, G,M, B and Y.

According to the present embodiment, by displaying the sub-frame imageof a primary color contained in a complementary color before or afterthe period for displaying the sub-frame image of the complementarycolor, it is possible to minimize the occurrence of the color breakupphenomena perceived by the human eye when the color video image isdisplayed by sequentially displaying the sub-frame images of therespective colors.

Further, by displaying the sub-frame images of the respective colors inthe order of R, C, G, M, B and Y within the period of one frame, it ispossible to limit the number of times each of three laser light sourcesis emitted to twice within the period of one frame. More specifically,the red laser light source (Red Laser) is emitted three times within theperiod of one frame shown in FIG. 39. However, if the period shown inFIG. 39 is repeated, the red laser light source emits an average of twotimes within one-frame period, and therefore the number of times the redlaser light source is emitted can be regarded as “2”. By increasing thenumber of times each of three laser light sources is emitted to “2” andby thus distributing the energy, it is possible to obtain a stableoutput of light sources by minimizing the heating of the laser lightsources due to continuous emission.

FIG. 41 exemplifies the case of displaying the sub-frame images of therespective colors of the three primary colors and three complementarycolors in the order of R, M, G, Y, B and C within the period of oneframe. As such, the present embodiment is configured to display, withinthe period of one frame, the sub-frame image of a first primary color,the sub-frame image of a complementary color containing the firstprimary color, the sub-frame image of the second primary color which isin a complementary relationship with the first complementary color, andthe sub-frame image of a second complementary color containing thesecond primary color, such as in the sequence of R, M, G and Y.

According to the present embodiment, the sub-frame image of a primarycolor contained in a complementary color is displayed before or afterthe sub-frame image of the complementary color, and therefore, it ispossible to minimize the occurrence of color breakup phenomena perceivedby the human eye when a color video image is displayed by sequentiallydisplaying the sub-frame images of the respective colors.

Further, by displaying the sub-frame images of the respective colors inthe order of R, M, G, Y, B and C within the period of one frame, it ispossible to limit the number of times each of three laser light sources(Red Laser, Green Laser and Blue Laser) included in the variable lightsource 1013 is emitted to twice within the period of one frame. Withthis operation, it is possible to obtain a stable output of the lightsource by minimizing the heating of the laser light source due tocontinuous emission, as in the example shown in FIG. 40.

FIG. 42 exemplifies the case of displaying the sub-frame images of thethree primary colors R, G and B and the three complementary colors C, M,and Y, and also of providing two periods for displaying the sub-frameimage of only G to which the human eye has the highest sensitivity,within the period of one frame, so as to cause the three laser lightsources in the variable light source 1013 to each emit light threetimes, within the period of one frame of an output video signal, therebyattaining the display of a color video image by sequentially displayingthe sub-frame images of the aforementioned colors.

In the example shown in FIG. 42, the sub-frame images of the threeprimary colors and three complementary colors are displayed in the orderof R, G1, M, G2, Y, B and C within the period of one frame. Morespecifically, the sub-frame of G is displayed twice, during the periodG1 and G2.

As such, the present embodiment is configured to display, within theperiod of one frame, the first sub-frame image of a first primary color,the sub-frame image of a first complementary color in a complementaryrelationship with the first primary color, the second sub-frame image ofthe first primary color, the sub-frame image of a second complementarycolor containing the first primary color, the sub-frame image of asecond primary color not contained in the second complementary color,the sub-frame image of the third complementary color, and the sub-frameimage of the third primary color, in the aforementioned order, such asin the order of R, G1, M, G2, Y, B and C.

According to the present example, before or after the sub-frame image ofa complementary color is displayed, the sub-frame image of the primarycolor contained in the complementary color is displayed, thereby makingit possible to suppress the occurrence of color breakup phenomena,perceived by the human eye when a color video image is displayed bysequentially displaying the sub-frame images of the colors.

Further, this configuration makes it possible to set the number of timeseach of the red and green laser light sources (Red Laser and GreenLaser) in the variable light source 1013 is emitted to three times. Byincreasing the number of times each of the red and green laser lightsources is emitted, energy is distributed, and the heating of the laserlight sources due to continuous emission (i.e., continuous turn-on) issignificantly suppressed, thereby making it possible to obtain a stableoutput of the light source.

More specifically, the present example is configured to provide, withinthe period of one frame, two periods for displaying the sub-frame imageof G, to which the human eye has the highest sensitivity. Alternately,it may be configured to provide two periods for displaying thesub-frames of a primary color, determined on the basis of the brightnessof individual colors in the video image represented by the input videosignal. The sub-frame image of R may be displayed twice if, for example,the video image represented by the input video signal is predominantlyred, such as a sunset.

FIG. 43 exemplifies the case of providing periods for displaying thesun-frame images of the three primary colors R, G and B and the threecomplementary colors C, M, and Y, and also of providing two periods, fordisplaying the sub-frame of each color of the three primary colors, soas to cause the three laser light sources included in the variable lightsource 1013 to emit light four times, within the period of one frame ofan output video signal, thereby projecting a color video image bysequentially displaying the sub-frame images of the aforementionedcolors.

In the example shown in FIG. 43, the sub-frame images of the threeprimary colors and three complementary colors are displayed in the orderof R1, C, R2, G1, M, G2, B1, Y and B2 within the period of one frame.More specifically, there are two periods for displaying the sub-frameimage of R, R1 and R2. Similarly, there are the two periods fordisplaying the sub-frame image of G, G1 and G2, and two periods fordisplaying the sub-frame image of B, B1 and B2.

As such, the present example is configured to provide three periods: 1.)a period for displaying the sub-frame image of a first complementarycolor (C), between the first and second sub-frame image display periodsof R1 and R2, to which color C has a complementary relationship, wherethe periods of R1 and R2 are obtained by dividing the video imagedisplay period for the first primary color (R) into two parts within theperiod of one frame; 2.) a period for displaying the sub-frame image ofa second complementary color (M) between the first and second sub-frameimage display periods of G1 and G2, to which color M has a complementaryrelationship, where the periods of G1 and G2 are obtained by dividingthe video image display period for the second primary color (G) into twoparts within the period of one frame; 3.) and a period for displayingthe sub-frame image of a third complementary color (Y) between the firstand second sub-frame image display periods of B1 and B2, to which colorY has a complementary relationship, where the periods of B1 and B2 areobtained by dividing the video image display period for the thirdprimary color (B) into two parts within the period of one frame, in theorder of R1, C, R2, G1, R2, G, M, G2, B1, Y and B2.

The present example is configured to set the number of times each of thethree laser light sources (Red Laser, Green Laser and Blue Laser) in thevariable light source 1013 is emitted at four times, within the periodof one frame. By increasing the number of times each of three laserlights sources emits light, for the period of one frame, the heating ofthe laser light sources due to continuous emission (i.e., continuousturn-on) is further suppressed, thereby making it possible to obtain astable output of the light sources.

Meanwhile, the present example shows an exemplary case of equipping twosub-frames for each primary color during the period of one frame.Alternately, it may be configured to equip a sub-frame by dividing theframe to units of LSBs, when a laser light source capable of repeating ahigh-speed turn-on and turn-off is used. Specifically, when green (G) isdisplayed with 8-bit data, the use of the above described non-binarydata makes it possible to perform a display by dividing the displayperiod of G into a maximum of 256 sub-frames.

As described above, the present embodiment is configured to specify thesequence for displaying the sub-frame images of the primary colors andthe complementary colors, within the period of one frame of an outputvideo signal. This makes it possible to suppress the occurrence of thecolor breakup phenomena, perceived by the human eye when the sub-frameimages of the different colors are displayed. Further, distributing ofenergy by increasing the number of times the laser light sources of thecolors R, G and B are emitted for each period of one frame makes itpossible to obtain a stable output of the light source by limiting theheating of the laser light source due to continuous emission (i.e.,continuous turn-on).

More specifically, the present embodiment has been described byexemplifying the case of displaying a color video image by displayingthe sub-frame images of different colors in sequence in the videodisplay system 1001, which generates the frame signals of the outputvideo signal at a higher frame rate than that of the input video signal.Alternately, it is possible to display a color video image by displayingthe sub-frame images of the respective colors in sequence by designatingthe sequence of the periods in a conventional video display system,which does not generate the frame signals of an output video signal at ahigher frame rate than that of the input video signal.

The first through fifth preferred embodiments have so far beendescribed.

Each of the embodiments has been described by exemplifying the videodisplay system 1001 shown in FIG. 4 as the video display system. Theembodiments, however, are not limited to the configuration shown in FIG.4. It is also possible to utilize another configuration as a videodisplay system. For example, the video display system 1001 may beconfigured display a color image by means of a color sequential methodof individually controlling the emission of the red, green, and bluelight sources in the variable light source 1013. Except for the case ofthe fifth embodiment, it is also possible to achieve the same resultsusing a color wheel.

FIG. 44 is a diagram showing an exemplary configuration of a videodisplay system attaining a color display using a color wheel.

The exemplary configuration shown in FIG. 44 is configured to equip thevideo display system 1001 (in FIG. 4) with a color wheel 1081, a motor1082 for rotating the color wheel 1081, and a motor controller 1083 forcontrolling the rotation of the motor 1082. Additionally, instead of thevariable light source 1013 in FIG. 4, a white light source 1084 isequipped in the configuration of FIG. 44.

The color wheel 1081 includes a filter for each of the colors (e.g., R,G and B), and is equipped between the rod type condenser body 1015 andsecond condenser lens 1016. Further, the configuration is such that afilter of an individual color is sequentially inserted into the lightpath of the light source optical system 1005 when the color wheel 1081is rotated.

The display processing unit 1006 is equipped with the motor controller1083, with the operational timing controlled by the sequencer 1035(refer to FIG. 5).

Further, the white light source 1084 is controlled by the light sourcecontroller 1019.

While the white light source 1084 is controlled under an emission statewith such a comprisal, the rotation of the color wheel 1081 iscontrolled to insert a corresponding color filter into the light path insynchronization with the sub-frame image of the colors to besequentially projected onto the screen 1012, in accordance with theframe signals of the output video signal. Thereby, a color image isdisplayed by means of a color sequential display method.

The video display system 1001 described above is a single-panel system,with one SLM 1002. However, a video display system may also beconfigured with a two-panel system, which are equipped with two SLMs1002.

FIGS. 45A, 45B, 45C and 45D are diagrams showing an exemplaryconfiguration of the optical comprisal of a two-panel video displaysystem. Further, FIG. 45A is a side view of the synthesis opticalsystem, which is the optical comprisal of the system; FIG. 45B is afront view thereof; FIG. 45C is a rear view thereof; and FIG. 45D is atop view thereof.

Referring to FIGS. 45A, 45B, 45C and 45D, the present synthesis opticalsystem includes a device package 1091 in which two SLMs 1002 areaccommodated, a color synthesis optical system 1092, a light sourceoptical system 1005, and variable light sources 1013 (i.e., 1013 r and1013 gb).

The two SLMs 1002 are accommodated in the device package 1091 such thatthe rectangular form of each SLM 1002 is inclined relative to each sideof the rectangular device package 1091, at approximately 45 degrees inthe horizontal plane.

The color synthesis optical system 1092 is placed on the device package1091.

The color synthesis optical system 1092 is constituted by triangularcolumnar prisms 1093 and 1094, which are adhesively attached togetheralong their lengths so as to form a right-angle triangular column, andby a right-angle triangular columnar light guide block 1095, which isadhesively attached to the side surface of the aforementioned prisms onthe slope surface of the light guide block 1095, with the bottom surfacethereof facing upward.

A light absorption body 1096 is equipped on the opposite of the prisms1093 and 1094.

The light source optical system 1005 of the variable light source 1013 r(i.e., the red laser light source 1013 r) and the light source opticalsystem 1005 of the variable light source 1013 gb (i.e., the green laserlight source 1013 g and blue laser light source 1013 b) are equipped onthe bottom surface of the light guide block 1095, with the optical axesof the variable light sources 1013 r and 1013 gb vertically aligned.

The illumination light 1008 emitted from the red laser light source 1013r is incident to the SLM 1002, positioned immediately underneath theprism 1093, as incident light 1009 by way of the light guide block 1095and the aforementioned prism 1093.

Meanwhile, the illumination lights 1008 emitted from the green laserlight source 1013 g and/or blue laser light source 1013 b are incidentto the SLM 1002 on the other side, positioned immediately underneath theprism 1094, as incident light 1009 by way of the light guide block 1095and the aforementioned prism 1094.

In the ON state of the mirror 1053, the green and/or blue incident light1009 incident to the SLM 1002 is reflected vertically upward asreflection light 1010 in the prism 1094, is further reflected by theexternal side surface and the joinder surface, in this order, of theaforementioned prism 1094, and is incident to the projection opticalsystem 1004, thus constituting a projection light 1011.

Also in the ON state of the mirror 1053, the red incident light 1009 isreflected vertically upward as reflection light 1010 in the prism 1093,is further reflected by the external side surface of the aforementionedprism 1093, is directed through the same light path as the green and/orblue reflection light 1010, and is incident to the projection opticalsystem 1004, thus constituting a projection light 1011.

As described above, two SLMs 1002 are accommodated in one device package1091 according to the video display system. Only the incident light 1009from the red laser light source 1013 r is irradiated on one SLM 1002.The incident light 1009 from the green laser light source 1013 g and/orblue laser light source 1013 b is irradiated on the other SLM 1002. Themodulation lights respectively modulated by the two SLMs 1002 arecondensed in the color synthesis optical system 1092 as described above.The condensed light is enlarged by the projection optical system 1004and is projected onto the screen 1012 as projection light 1011.

FIG. 46 is a diagram showing an exemplary configuration of a circuit fora video display system, including the optical comprisal shown in FIGS.45A through 45D.

As shown in FIG. 46, the exemplary circuit configuration of the presentvideo display system is different from that of the video display system1001 shown in FIG. 5, in that the former comprises two systems,including the SLM controller 1018, SLM 1002, light source controller1019, and variable light source 1013, as the later-stage circuits of theimage processing unit 1017.

Of the two systems shown in FIG. 46, one system includes the variablelight source 1013 r, the light source controller 1019 used forcontrolling the variable light source 1013 r, and the SLM controller1018 used for controlling the light source controller 1019 and the SLM1002 which modulates the red incident light 1009.

The other system includes the variable light source 1013 gb, the lightsource controller 1019 used for controlling the variable light source1013 gb, and the SLM controller 1018 used for controlling the lightsource controller 1019 and the SLM 1002 which modulates the green and/orblue incident lights 1009.

Further, in the present video display system, the signal conversion unit1034 converts the frame signal of a video signal output from the frameinterpolation unit 1033 into a frame signal having the color informationof R and a frame signal having the color information of at least onecolor of G, B and C. Then, the frame signal having the color informationof R is inputted into the SLM controller 1018 used for controlling theSLM 1002 which modulates the red incident light 1009, while the framesignal having the color information of at least one color of G B and Cis inputted into the SLM controller 1018 used for controlling the SLM1002 which modulates the green and/or blue incident light 1009.

Further, the frame interpolation unit 1033 processes in accordance witha control signal outputted from the respective sequencers 1035 of thetwo SLM controllers 1018. The frame synchronous signals generated by theframe interpolation unit 1033 are inputted into the respectivesequencers 1035 of the two SLM controllers 1018.

The configuration as described controls both the red laser light source1013 r and SLM 1002 used for modulating the red incident light 1009 andcontrols both the variable light source 1013 gb and the SLM 1002 usedfor modulating the green and/or blue incident light 1009, in accordancewith the frame signals of the output video signal, thereby making itpossible to attain a color display.

Note that, except for in the case of the fifth embodiment, the two-panelvideo display system is also capable of attaining a color display usinga color wheel.

FIG. 47 is an exemplary configuration of such a case.

In contrast to the above described video display system, the exemplaryconfiguration shown in FIG. 47 is equipped with a color wheel 1081, amotor 1082 for rotating the color wheel 1081, and a motor controller1083 for controlling the rotation of the motor 1082. In addition, thevariable light source 1013 is replaced with a white light source 1084.

In the exemplary configuration shown in FIG. 47, the white light source1084 is controlled by the light source controller 1019, and the lightsource controller 1019 and two SLMs 1002 are controlled by a single SLMcontroller 1018.

The color wheel 1081 has the filters of a plurality of colors (e.g., R,G and B), and is equipped between the color synthesis optical system1092 and projection optical system 1004. The configuration is such thatthe filters of the respective colors are sequentially inserted into thelight path of the projection optical system 1004 when the color wheel1081 is rotated.

The motor controller 1083 is equipped in the display processing unit1006 and the operational timing of the motor controller 1083 iscontrolled by the SLM controller 1018.

With such a comprisal, the two SLMs 1002 and the rotation of the colorwheel 1081 are controlled in accordance with the frame signal of theoutput video signal, after controlling the white light source 1084 underan emission state, and thereby a color display by means of a colorsequential method can be attained.

Whereas the present invention has been described in detail, the presentinvention may, of course, be improved or modified in various mannerspossible within the scope and spirit of the present invention and is notlimited to the above described embodiments.

For example, it is possible to combine the configurations and/oroperations put forth in the above described first through fifthembodiments.

As such, the present invention can reduce degradation in the gray scaleof a video image, as perceived by the human eye, while decreasing theinformation volume of a high frame-rate frame signal to be generated, soas to not increase the load of the video image processing and displayprocessing.

Although the present invention has been described in terms of thepresently preferred embodiment, it is to be understood that suchdisclosure is not to be interpreted as limiting. Various alternationsand modifications will no doubt become apparent to those skilled in theart after reading the above disclosure. Accordingly, it is intended thatthe appended claims be interpreted as covering all alternations andmodifications as fall within the true spirit and scope of the invention.

1. A video display system, comprising: a plurality of primary colorlight sources; a spatial light modulator (SLM) for modulating anillumination light emitted from at least one of the plurality of primarylight sources, wherein a display controller for controlling a process todisplay a sequence of video images within a period of one framecomprising each of a plurality of primary colors and each of a pluralityof complementary colors to minimize a number of emissions of each of theplurality of primary color light sources and also displaying the videoimages of the colors of the plurality of primary colors and theplurality of complementary colors in sequence; the display controllercontrolling a display of the sequence of video images within the periodof one frame according to a order of: (a) the video image of a firstprimary color, (b) the video image of a first complementary colorcontaining the first primary color, (c) the video image of a secondprimary color contained in the first complementary color, and (d) thevideo image of a second complementary color containing, the secondprimary color.
 2. The video display system according to claim 1,wherein: the plurality of primary colors comprising three colors of ared (R) color, a green (G) color and a blue (B) color, and the pluralityof complementary colors comprising three colors of cyan (C) color, amagenta (M) color and a yellow (Y) color.
 3. A video display system,comprising: a plurality of primary color light sources; and a spatiallight modulator (SLM) for modulating an illumination light emitted fromat least one of the plurality of primary light sources, wherein adisplay controller for controlling a process to display a sequence ofvideo images within a period of one frame comprising of each of aplurality of primary colors and each of a plurality of complementarycolors to maximize a number of emissions of each of the plurality ofprimary color light sources and also displaying the video images of thecolors of the plurality of primary Colors and the plurality ofcomplementary colors in sequence; and the display controller controllinga display of the sequence of video images within the period of one frameaccording to a order of: (a) the video image of a first primary color,(b) the video image of a first complementary color containing the firstprimary color, (c) the video image of a second primary color containedin the first complementary color, and (d) the video image of a secondcomplementary color containing the second primary color.
 4. The videodisplay system according to claim 3, wherein: the plurality of primarycolors comprising three colors of a red (R) color, a green (G) color anda blue (B) color, and the plurality of complementary colors comprising,three colors of can t C) color, a magenta (M) color and a yellow (Y)color.
 5. A video display system comprising: a plurality of primarycolor light sources; and a spatial light modulator (SLM) for modulatingan illumination light emitted from at least one of the plurality ofprimary light sources, wherein a display controller for controlling aprocess to display a sequence of video images within a period of oneframe comprising of each of a plurality of primary colors and each of aplurality of complementary colors to maximize a number of emissions ofeach of the plurality of primary color light sources and also displayingthe video images of the colors of the plurality of primary colors andthe plurality of complementary colors in sequence; the displaycontroller controlling a display of the sequence of video images withinthe period of one frame according to the order of: (a) the video imageof as first primary color, (b) the video image of a first complementarycolor containing the first primary color, (c) the video image of asecond primary color that is in a complementary relationship with thefirst complementary color, and (d) the video image of a secondcomplementary color containing the second primary color.
 6. A videodisplay system comprising: a plurality of primary color light sources;and a spatial light modulator (SLM) for modulating an illumination lightemitted from at least one of the of primary light sources, wherein adisplay controller for controlling a process to disease sequence ofvideo images within a period of one frame comprising of each of aplurality of primary colors and each of a plurality of complementarycolors to maximize a number of emissions of each of the plurality ofprimary color light sources and also displaying the video images of thecolors of the plurality of primary colors and the plurality ofcomplementary colors in sequence: the display controller controlling adisplay of the sequence of video images within the period of one frameaccording to the order of: (a) the first video image of a first primarycolor, (b) the video image of a first complementary color that is in acomplementary relationship with the first primary color, (c) the secondvideo image of the first primary color, (d) the video image of a secondcomplementary color containing the first primary color, (e) the videoimage of a second primary color not contained in the secondcomplementary color, (f) the video image of a third complementary color(g) the video image of a third primary color.
 7. The video displaysystem according to claim 6, wherein: the display controlling thedisplay of the video image of the first primary color based on a colorvisibility to the human eye.
 8. The video display system according toclaim 6, wherein: the display controlling the display of the video imageof the first primary color based on a brightness of each color in thevideo image represented by an input video signal.
 9. A video displaysystem comprising: plurality of primary color light sources; and aspatial light modulator (SLM) for modulating an illumination lightemitted from at least one of the plurality of primary light sources,wherein a display controller for, controlling a process to display asequence of video images within a period of one frame comprising of eachof a plurality of primary colors and each of a plurality ofcomplementary colors to maximize a number of emissions of each of theplurality of primary color light sources and also displaying the videoimages of the colors of the plurality of primary colors and theplurality of complementary colors in sequence; the display controllercontrols a period for displaying the video image of a firstcomplementary color complementary to the first primary color between adisplay period P1 for the first video image of the first primary colorand a display period P2 for the second video image of the first primarycolor, where the display periods P1 and P2 are obtained by dividing adisplay period with the period of one frame for the video image of thefirst primary color into two periods; the display controller controls aperiod for displaying the video image of a second complementary colorcomplementary to the second primary color between a display period P3for the first video image of the second primary color and a displayperiod P4 for the second video image of the second primary color, wherethe display periods P3 and P4 are obtained by dividing the displayperiod for the video image of the second primary color within the periodof one frame into two periods, and the display controller controls aperiod for displaying the video image of a third complementary colorcomplementary to the third primary color between a display period P5 forthe first video image of the third primary color and a display period P6for the second video image of the third primary color, where the displayperiods P5 and P6 are obtained, by dividing the display period for thevideo image of the third primary color within the period of one frameinto two periods.
 10. A video display system, comprising: an imageprocessing unit receives continuously an input video signal includinginput frame signals for generating an output video signal having ahigher frame rate than the input video signal; and a spatial lightmodulator (SLM) applies the output video signal for modulating anillumination light, wherein the image processing unit further receivesan individual frame signal of the input video signal into a frame forsequentially displaying a plurality of sub-frame video images indifferent colors within a display frame, and the image processing unitfurther generates the output video signal includes a frame signal forsequentially displaying the sub-frame video images of different colors,wherein a number of gray scale levels of a sub-frame video image of eachcolor of the output video signal is smaller, or smaller in a part ofsub-frame images, than a number of gray scale levels of a sub-framevideo image of each color of the input video signal.
 11. The videodisplay system according to claim 10, wherein: the image processing unitreceives the input video signal comprising the sub-frame video imagesfurther comprise at: least three colors of a red (R) color, a green (G)color and a blue (B) color, and the image processing unit generates theoutput video signal comprising the sub-frame video images for displayingimages of at least three primary colors of red, green and blue colorsand three complimentary colors of cyan (C), magenta (M) and yellow (Y)colors.
 12. The video display system according to claim 10, wherein: theimage processing units receives the input video signals comprisingsub-frame video images for displaying at least three colors of a red(R)color, a green (G) color and a blue (B) color, and the imageprocessing unit generates the output video signal includes a framesignal to sequentially display the sub-frame video images of at leastthe red, green and blue colors, and a frame signal to display thesub-frame video image of one color among a white (W) color, a gray (Gy)color and a black (K) color.
 13. The video display system according toclaim 10, wherein: the image processing unit receives the video inputsignal including a frame signal to sequentially display sub-frame videoimages of a plurality of colors comprising sub-frame signals for atleast three primary colors of a red (R) color, a green (G) color and ablue (B) color, and the image processing unit generates the output videosignal includes a frame signal including sub-frame signals tosequentially display the sub-frame video images of at least the threeprimary colors and at least one complementary color, wherein thesub-frame video image of the at least one complementary color issandwiched between the sub-frame video images of two adjacent primarycolors for sequentially displaying a frame signal of the output videosignal.
 14. The video display system according to claim 13, wherein: theimage processing units generates the output video signals including thesub-frame signals of a first complementary color containing a firstprimary color subsequent to the sub-frame signal of the first primarycolor, and the sub-frame signal of a second primary color without thefirst complementary color subsequent to the sub-frame signal of thefirst complementary color.
 15. The video display system according toclaim 10, wherein: the image processing unit generates the output videosignal including at least a sub-frame signal for displaying a videoimage of one color having a fewer number of gray scale levels than thesub-frame signals for displaying video images of other colors.
 16. Thevideo display system according to claim 10, wherein: the imageprocessing unit generates the output video signal including at least asub-frame signal for displaying a video image of one color having itlarger number of times of displaying per frame period than the sub-framesignals for displaying video images of other colors.
 17. The videodisplay system according to claim 10, wherein; the image processing unitgenerates the output video signal including at least a sub-frame signalfor displaying a video image of one color having two-bit, or less, grayscale data per pixel.
 18. The video display system according to claim10, wherein: the image processing unit generates the output video signalincluding one sub-frame signal for displaying video images of theplurality of colors sequentially having a sub-frame rate greater than orequal to 540 Hz.
 19. The video display system according to claim 10,wherein: the image processing unit generates the output video signalincluding o sub-frame signal for displaying video images of theplurality of colors sequentially having a sub-frame rate greater than orequal to 1080 Hz.
 20. The video display system according to claim 10,wherein: the SLM further comprising a mirror device implemented with aplurality of deflectable micromirrors.
 21. A video display systemcomprising: an image processing unit receives continuously an inputvideo signal including input frame signals for generating an outputvideo signal including output frame signals having a higher frame ratethan the input frame signals; and a spatial light modulator (SLM)applies the output frame signals for modulating an illumination light,wherein the input frame signal comprises signals to sequentially displaysub-frame video images of a plurality of colors, the image processingunits generates the output video signal includes sub-frame signals ofthe plurality of colors applied to the SLM to carry out a modulationprocess to sequentially display the sub-frame video images of theplurality of colors; and a number of gray scale levels of a sub-framevideo image of each color of the output video signal is smaller, orsmaller in a part of sub-frame images, than a number of gray scalelevels of a sub-frame video image of each color of the input videosignal.
 22. The video display system according to claim 21 furthercomprising: a plurality of semiconductor light sources emittingdifferent color lights, wherein each of the plurality of semiconductorlight sources synchronously emits light with the sub-frame signals ofthe frame signals included in the output video signal for displayingvideo image of a same color synchronously.
 23. The video display systemaccording to claim 21 further comprising: as plurality of semiconductorlight sources emitting different color lights, wherein an emission cycleof each of the semiconductor light sources for emitting each color isshorter than a cycle of the sub-frame signal for displaying thesub-frame video images of the corresponding same colors according to aframe signal of the input video signal.
 24. The video display systemaccording to claim 21, wherein: the image processing unit receives thesub-frame video signals for displaying the sub-frame video images of aplurality of colors further include a sub-frame video signal fordisplaying a sub-frame video image of a blue (B) color having a smallernumber of gray scale levels than the number of gray scale levels fordisplaying the sub-frame video images of other colors.
 25. The videodisplay system according to claim 21, wherein: the image processing unitreceives the sub-frame video signals for displaying the sub-frame videoimages of a plurality of colors includes the sub-frame signals fordisplaying sub-frame video image of one color among white (W), gray (Gy)and black (K), with a smaller number of gray scale levels than thenumber of gray scale levels of the sub-frame signals for displayingvideo images of other colors.
 26. The video display system according toclaim 21, further comprising: a plurality of semiconductor light sourcesfor emitting different color lights, wherein said plurality ofsemiconductor light sources further emits a white illumination light bysimultaneously emitting the plurality of semiconductor light sources.27. The video display system according to claim 21, wherein: a pluralityof the semiconductor light sources of different colors emit acolor-combined illumination light, wherein each of the plurality ofsemiconductor light sources for each of said colors are controlled tosynchronously change an emission pattern according to the outputsub-frame video signal for displaying sub-frame video image of acorresponding color.
 28. The video display system according to claim 21,wherein: the SLM further comprising a mirror device implemented with aplurality of deflectable micromirrors.